Can you really be addicted to food? Researchers are uncovering convincing similarities to drug addiction

Source: The Conversation – USA (3) – By Claire Wilcox, Adjunct Faculty in Psychiatry, University of New Mexico

Research has found that high-sugar, ultraprocessed foods can be addictive for some people. Doucefleur/iStock via Getty Images Plus

People often joke that their favorite snack is “like crack” or call themselves “chocoholics” in jest.

But can someone really be addicted to food in the same way they could be hooked on substances such as alcohol or nicotine?

As an addiction psychiatrist and researcher with experience in treating eating disorders and obesity, I have been following the research in this field for the past few decades. I have written a textbook on food addiction, obesity and overeating disorders, and, more recently, a self-help book for people who have intense cravings and obsessions for some foods.

While there is still some debate among psychologists and scientists, a consensus is emerging that food addiction is a real phenomenon. Hundreds of studies have confirmed that certain foods – often those that are high in sugar and ultraprocessedaffect the brains and behavior of certain people similarly to other addictive substances such as nicotine.

Still, many questions remain about which foods are addictive, which people are most susceptible to this addiction and why. There are also questions as to how this condition compares to other substance addictions and whether the same treatments could work for patients struggling with any kind of addiction.

How does addiction work?

The neurobiological mechanisms of addiction have been mapped out through decades of laboratory-based research using neuroimaging and cognitive neuroscience approaches.

Studies show that preexisting genetic and environmental factors set the stage for developing an addiction. Regularly consuming an addictive substance then causes a rewiring of several important brain systems, leading the person to crave more and more of it.

This rewiring takes place in three key brain networks that correspond to key functional domains, often referred to as the reward system, the stress response system and the system in charge of executive control.

First, using an addictive substance causes the release of a chemical messenger called dopamine in the reward network, which makes the user feel good. Dopamine release also facilitates a neurobiological process called conditioning, which is basically a neural learning process that gives rise to habit formation.

As a result of the conditioning process, sensory cues associated with the substance start to have increasing influence over decision-making and behavior, often leading to a craving. For instance, because of conditioning, the sight of a needle can drive a person to set aside their commitment to quit using an injectable drug and return to it.

Second, continued use of an addictive substance over time affects the brain’s emotional or stress response network. The user’s body and mind build up a tolerance, meaning they need increasing amounts of the substance to feel its effect. The neurochemicals involved in this process are different than those mediating habit formation and include a chemical messenger called noradrenaline and internally produced opioids such as endorphins. If they quit using the substance, they experience symptoms of withdrawal, which can range from irritability and nausea to paranoia and seizures.

At that point, negative reinforcement kicks in. This is the process by which a person keeps going back to a substance because they’ve learned that using the substance doesn’t just feel good, but it also relieves negative emotions. During withdrawal from a substance, people feel profound emotional discomfort, including sadness and irritability. Negative reinforcement is why someone who is trying to quit smoking, for instance, will be at highest risk of relapse in the week just after stopping and during times of stress, because in the past they’d normally turn to cigarettes for relief.

Third, overuse of most addictive substances progressively damages the brain’s executive control network, the prefrontal cortex, and other key parts of the brain involved in impulse control and self-regulation. Over time, the damage to these areas makes it more and more difficult for the user to control their behavior around these substances. This is why it is so hard for long-term users of many addictive substances to quit.

Scientists have learned more about what’s happening in a person’s brain when they become addicted to a substance.

What evidence is there that food is addictive?

Many studies over the past 25 years have shown that high-sugar and other highly pleasurable foods – often foods that are ultraprocessed – act on these brain networks in ways that are similar to other addictive substances. The resulting changes in the brain fuel further craving for and overuse of the substance – in this case, highly rewarding food.

Clinical studies have demonstrated that people with an addictive relationship to food demonstrate the hallmark signs of a substance use disorder.

Studies also indicate that for some people, cravings for highly palatable foods go well beyond just a normal hankering for a snack and are, in fact, signs of addictive behavior. One study found that cues associated with highly pleasurable foods activate the reward centers in the brain, and the degree of activation predicts weight gain. In other words, the more power the food cue has to capture a person’s attention, the more likely they are to succumb to cravings for it.

Multiple studies have also found that suddenly ending a diet that’s high in sugar can cause withdrawal, similar to when people quit opioids or nicotine.

Excessive exposure to high-sugar foods has also been found to reduce cognitive function and cause damage to the prefrontal cortex and hippocampus, the parts of the brain that mediate executive control and memory.

In another study, when obese people were exposed to food and told to resist their craving for it by ignoring it or thinking about something else, their prefrontal cortexes were more active compared with nonobese individuals. This indicates that it was more difficult for the obese group to fight their cravings.

drawing of a woman in a spiral surrounded by processed foods
Researchers are still working out the best methods to help patients with food addictions develop a healthy relationship with food.
Viktar Sarkisian/iStock via Getty Images Plus

Finding safe treatments for patients struggling with food

Addiction recovery is often centered on the idea that the fastest way to get well is to abstain from the problem substance. But unlike nicotine or narcotics, food is something that all people need to survive, so quitting cold turkey isn’t an option.

In addition, eating disorders such as bulimia nervosa and binge-eating disorder often occur alongside addictive eating. Most psychologists and psychiatrists believe these illnesses have their root cause in excessive dietary restriction.

For this reason, many eating disorder treatment professionals balk at the idea of labeling some foods as addictive. They are concerned that encouraging abstinence from particular foods could trigger binge eating and extreme dieting to compensate.

A way forward

But others argue that, with care, integrating food addiction approaches into eating disorders treatment is feasible and could be lifesaving for some.

The emerging consensus around this link is moving researchers and those who treat eating disorders to consider food addiction in their treatment models.

One such approach might look like the one described to me by addiction psychiatrist and eating disorders specialist Dr. Kim Dennis. In line with traditional eating disorder treatment, nutritionists at her residential clinic strongly discourage their patients from restricting calories. At the same time, in line with traditional addiction treatment, they help their patients to consider significantly reducing or completely abstaining from particular foods to which they have developed an addictive relationship.

Additional clinical studies are already being carried out. But going forward, more studies are needed to help clinicians find the most effective treatments for people with an addictive relationship with food.

Efforts are underway by groups of psychologists, psychiatrists, neuroscientists and mental health providers to get “ultraprocessed food use disorder,” also known as food addiction, into future editions of diagnostic manuals such as the Diagnostic and Statistical Manual of Mental Disorders and the World Health Organization’s International Classification of Diseases.

Beyond acknowledging what those treating food addiction are already seeing in the field, this would help researchers get funding for additional studies of treating food addiction. With more information about what treatments will work best for whom, those who have these problems will no longer have to suffer in silence, and providers will be better equipped to help them.

The Conversation

I have two books for sale which address food addiction, and I could benefit financially from increased interest in the food addiction topic:

Wilcox C.E. Food Addiction Obesity and Disorders of Overeating: An Evidenced Based Assessment and Clinical Guide. (2021) Springer

Wilcox C. Rewire Your Food-Addicted Brain: Fight Cravings and Break Free from a High-Sugar Ultra-Processed Diet. (2025) New Harbinger Publications

ref. Can you really be addicted to food? Researchers are uncovering convincing similarities to drug addiction – https://theconversation.com/can-you-really-be-addicted-to-food-researchers-are-uncovering-convincing-similarities-to-drug-addiction-261727

Flu season has arrived – and so have updated flu vaccines

Source: The Conversation – USA (3) – By Libby Richards, Professor of Nursing, Purdue University

The flu vaccine is updated every year to include the strains known to be circulating. Cecilie_Arcurs/E+ via Getty Images

As the autumn’s cool weather settles in, so does flu season – bringing with it the familiar experiences of sniffles, fever and cough.

Every year, influenza – the flu – affects millions of people. Most will experience the infection as a mild to moderate illness – but for some, it can be severe, potentially resulting in hospitalization and even death.

While the start of flu season may feel routine, it’s important to remember that the virus changes every year, making annual vaccination an important part of staying healthy.

What to expect this flu season

Public health experts are closely watching how this year’s flu season unfolds. Early reports suggest that the U.S. may see a moderate level of flu cases, partly because last year’s flu activity was high and it’s uncommon to have two severe flu seasons in a row.

However, the U.S. also uses data from the Southern Hemisphere’s earlier flu season, which lasts from April to October, to help predict what the season might look like. There, the flu season has been more severe than in years past.

Taken together, that means there could be a significant number of flu cases in the U.S., particularly among children, older adults and those with chronic health conditions.

Each year, the flu vaccine is updated to best match the strains of influenza expected to circulate. Because flu viruses mutate frequently, the effectiveness of the flu vaccine can vary each year. However, even when the match between the seasonal flu and the vaccine that is designed around it isn’t perfect, vaccination remains the best protection against severe illness.

In the U.S., all flu vaccines for the 2025-2026 season will be trivalent – which means they are formulated to protect against the three main groups of influenza virus strains. These are an A (H1N1) virus, an A (H3N2) virus and a B/Victoria virus.

A family, mom, dad and two young children all sit in bed together blowing their noses.
The flu vaccine protects against severe illness from an influenza infection.
Jacob Wackerhausen/iStock via Getty Images Plus

Vaccine availability

Recent vaccine policy changes have created some confusion, particularly around COVID-19 vaccines. Many people are wondering if getting the flu vaccine has become more complicated. The good news is that flu vaccines remain widely available and accessible. Pharmacies, doctors’ offices, public health clinics and many workplaces are offering the seasonal shot, often at little or no cost.

The 2025-2026 flu vaccine is available now. Manufacturers start shipping vaccines doses in July and August to ensure access by September. While public health experts won’t know the exact effectiveness of the flu vaccine until flu season is over, the flu shot usually cuts your chances of needing to see a doctor for the flu by about half.

Vaccination helps reduce the severity of illness, the likelihood of hospitalization and the spread of infection within our communities.

It’s important to note that you can get the flu shot at the same time as other vaccines, such as the COVID-19 vaccine or the RSV and pneumonia vaccines for older adults, without compromising effectiveness. If you’re unsure which vaccines are right for you, your health care provider or pharmacist can help you decide based on your age and health status.

Who should get the flu shot

The Centers for Disease Control and Prevention recommends that everyone 6 months and older receive the flu vaccine each year, with rare exceptions. That aligns with guidelines from other organizations, such as the American Association of Pediatrics.

The flu vaccine is especially important for:

• Adults 65 and older

• Children under 5 – and particularly those under 2

• Pregnant people

• People with chronic conditions such as asthma, diabetes or heart disease

• Health care workers and caregivers

Even if you’re healthy and rarely get sick, getting vaccinated protects not only you but also those around you who may be more vulnerable.

Practical prevention tips

In addition to vaccination, everyday actions help reduce the spread of flu and other respiratory viruses:

Wash your hands frequently with soap and water.

• Cover your coughs and sneezes.

• Stay home if you’re feeling unwell.

• Consider wearing a mask in crowded indoor spaces during peak flu activity, particularly if you have a cough.

Even though flu season is part of life, serious illness doesn’t have to be. By staying informed, getting vaccinated and practicing healthy habits, everyone can play a role in keeping their communities safe and healthy.

If you haven’t gotten your flu shot yet, now’s the time to protect yourself, and those you care for, this flu season.

The Conversation

Libby Richards has received funding from the American Nurses Foundation, National Institutes of Health, and the Indiana Clinical and Translational Sciences Institute .

ref. Flu season has arrived – and so have updated flu vaccines – https://theconversation.com/flu-season-has-arrived-and-so-have-updated-flu-vaccines-267058

How pollution and the microbiome interact with Tregs, the immune system regulators whose discovery was honored with the Nobel Prize

Source: The Conversation – USA (3) – By Prakash Nagarkatti, Professor of Pathology, Microbiology and Immunology, University of South Carolina

Treg cells have been thrust into the limelight thanks to the Nobel Prize-winning work of a team of researchers from the U.S. and Japan. jarun011/iStock via Getty Images Plus

A special group of immune cells known as regulatory T cells, or Tregs for short, became an overnight sensation when a trio of U.S. and Japanese scientists won the Nobel Prize in physiology or medicine on Oct. 6, 2025, for their discovery and elucidation of these cells.

Treg cells act as the “master regulators” of the immune system – much like conductors leading an orchestra – ensuring that all other immune cells work in harmony. People with too few or defective Treg cells often develop autoimmune diseases, where unchecked immune cells mistakenly attack the body’s own tissues or organs. Yet when Treg cells become too numerous, people can become more susceptible to cancer and infections.

For this reason, Treg cells are often described as a double-edged sword. Treg cells also control internal revolt in the form of an overactive immune response by other immune cells that can trigger allergies and autoimmune diseases such as arthritis, lupus and multiple sclerosis – diseases that develop when Treg cells are defective in either number, function or both.

The well-established functions of Treg cells in autoimmune diseases, cancer and infections have recently been complemented by research unraveling how environmental factors influence these cells and modulate the immune response.

We are a husband-wife team of immunologists who study how environmental factors such as chemicals, diet and gut bacteria affect Treg cells and the overall functioning of the immune system.

While our study dating back to 1984 found that certain environmental contaminants induce T cells that suppress the immune system, further study on such cells was hampered by an inability in the field at large to isolate and characterize these cells. The discoveries honored by this year’s Nobel Prize transformed how researchers understand the immune system.

Nobel-Prizing winning scientist showing extreme emotion.
One of the three Nobel Prize-winning researchers, Mary E. Brunkow, responds emotionally as she receives the news of the prize.
AP Photo/Lindsey Wasson

The interplay of environmental factors

The environment plays a profound role in regulating the development, maintenance and functions of Treg cells. Some examples of environmental factors include chemical pollutants found in the air and water, microbes, sunlight, diet and medications.

Rather than being a single, static population, Treg cells are highly adaptable. They integrate a variety of environmental cues to either suppress or manage immune responses. They accomplish this by producing key molecules such as FoxP3 that send a signal to other immune cells to stop mounting an aggressive immune response.

Certain toxic chemicals can increase the number or activity of Treg cells. One of the best-known examples is a group of long-lasting pollutants called dioxins that accumulate in fatty tissues through consumption of contaminated meat, dairy and fish. They are produced from burning waste as well as chemical manufacturing and forest fires.

The most toxic dioxin, 2,3,7,8-tetrachlorodibenzo-p-dioxin, or TCDD, is a known human carcinogen. Researchers have linked exposure to this chemical to various health problems, including cancer and reproductive and developmental issues. Research shows that dioxins activate Treg cells through a sensor known as the aryl hydrocarbon receptor. This constitutes one of the mechanisms through which certain environmental chemicals promote cancer by enhancing Treg activity and suppressing the anti-cancer immune response.

Air pollution, such as diesel exhaust, can have the opposite effect, impairing Treg cell function and contributing to inflammatory diseases such as asthma. This may occur through damage to the FoxP3 gene.

Colorful illustration of five types of T cells against a white background.
Regulatory T cells, or Treg cells, are one of at least five major types of T cells.
ttsz/iStock via Getty Images Plus

How diet interacts with Treg cells

Diet also plays a powerful role in regulating Treg cells. Compounds known as indoles, found in vegetables from the cabbage family such as broccoli, cabbage and cauliflower, can activate Treg cells and help prevent gut inflammation. These compounds also work by stimulating the aryl hydrocarbon receptor, which boosts Treg numbers and activity.

Another way diet can influence Treg cells is through the regulation of the microbes that live in the gut.

The gut has trillions of microbial residents, both benefical and harmful. Previous research found that Treg cells in the gut play a crucial role in maintaining gut homeostasis – the dynamic balance between microbiota and immune cells found in the gut. Any disturbance leading to loss of Treg cell function can lead to hyperactivation of other immune cells in the gut. This can trigger inflammation in which the immune cells destroy the lining of the intestine, leading to conditions such as inflammatory bowel disease.

Other naturally occurring substances – such as naringenin, a chemical abundant in citrus fruits, and epigallocatechin-3-gallate, a compound found in green tea – also activate the aryl hydrocarbon receptor and promote Treg development.

A fiber-rich diet supports the growth of beneficial gut bacteria. This bacteria ferments fiber into short-chain fatty acids that enhance Treg cell function and help maintain gut health. Probiotic bacteria also increases Treg cell populations, thereby reducing inflammation.

In addition, dietary tryptophan – an amino acid found in foods such as poultry, eggs, tofu and seeds – is metabolized into compounds that activate the aryl hydrocarbon receptor, further boosting Treg cell activity and protecting against gut inflammation.

By contrast, a Western diet high in fat, sugar and processed foods disrupts the balance of gut bacteria. This, in turn, reduces the population of microbes that support Treg cells and promotes a more inflammatory environment in the gut.

Keeping Treg cells in harmony

Scientists like us and many others are working to understand the processes involved in maintaining the delicate balance of Treg cells that are influenced by all of these outside factors. The goal is to learn how Treg cells and other immune cells can be kept in equilibrium – strong enough to defend against infections and cancer yet restrained enough to prevent autoimmune and inflammatory diseases.

The profound environmental influence on Treg cell development and function makes understanding these interactions crucial for defining the fine line between health and disease.

The Conversation

Prakash Nagarkatti receives funding from the National Institutes of Health.

Mitzi Nagarkatti receives funding from the National Institutes of Health.

ref. How pollution and the microbiome interact with Tregs, the immune system regulators whose discovery was honored with the Nobel Prize – https://theconversation.com/how-pollution-and-the-microbiome-interact-with-tregs-the-immune-system-regulators-whose-discovery-was-honored-with-the-nobel-prize-266865

The new president of The Church of Jesus Christ of Latter-day Saints will inherit a global faith far more diverse than many realize

Source: The Conversation – USA (3) – By Brittany Romanello, Assistant Professor of Sociology, University of Arkansas

Missionary Sayon Ang holds up a sign signifying she speaks Cambodian during the twice-annual conference of The Church of Jesus Christ of Latter-day Saints on Oct. 4, 2014, in Salt Lake City. AP Photo/Kim Raff

The Church of Jesus Christ of Latter-day Saints has spent the past few weeks in a moment of both mourning and transition. On Sept. 28, 2025, a shooting and arson at a Latter-day Saints meetinghouse in Michigan killed four people and wounded eight more. What’s more, Russell M. Nelson, president of the church, died the day before at age 101. Based on protocol, his role will most likely be filled by Dallin H. Oaks, the longest-serving of the church’s top leaders.

The next president will inherit leadership of a religious institution that is both deeply American and increasingly global – diversity at odds with the way it’s typically represented in mainstream media, from “The Secret Life of Mormon Wives” to “The Book of Mormon” Broadway musical.

As a cultural anthropologist and ethnographer, I research Latter-day Saints communities across the United States, particularly Latina immigrants and young adults. When presenting my research, I’ve noticed that many people still closely associate the church with Utah, where its headquarters are located.

An ornate white building with a tall spire, and green mountains in the background.
The Latter-day Saints temple in Cochabamba, Bolivia, was dedicated in 2000.
Parallelepiped09/Wikimedia Commons, CC BY-SA

The church has played a pivotal role in Utah’s history and culture. Today, though, only 42% of its residents are members. The stereotype of Latter-day Saints as mostly white, conservative Americans is just one of many long-standing misconceptions about LDS communities and beliefs.

Many people are surprised to learn there are vibrant congregations far from the American West’s “Mormon Corridor.” There are devout Latter-day Saints everywhere from Ghana and the United Arab Emirates to Russia and mainland China.

Global growth

Joseph Smith founded The Church of Jesus Christ of Latter-day Saints in upstate New York in 1830 and immediately sent missionaries to preach along the frontier. The first overseas missionaries traveled to England in 1837.

Shortly after World War II, church leaders overhauled their missionary approach to increase the number of international missions. This strategy led to growth across the globe, especially in Central America, South America and the Pacific Islands.

Today, the church has over 17.5 million members, according to church records. A majority live outside the U.S., spread across more than 160 countries.

One way the church and researchers track this global growth is by construction of new temples.These buildings, used not for weekly worship but special ceremonies like weddings, were once almost exclusively located in the United States. Today, they exist in dozens of countries, from Argentina to Tonga.

During Nelson’s presidency, which began in 2018, he announced 200 new temples, more than any of his predecessors. Temples are a physical and symbolic representation of the church’s commitment to being a global religion, although cultural tensions remain.

Two men in suits walk by a large map of the world framed on the wall of a hallway.
Two missionaries for The Church of Jesus Christ of Latter-day Saints walk through the Missionary Training Center in Provo, Utah, in 2008.
AP Photo/George Frey

Among U.S. members, demographics are also shifting. Seventy-two percent of American members are white, down from 85% in 2007, according to the Pew Research Center. Growing numbers of Latinos – 12% of U.S. members – have played a significant role sustaining congregations across the country.

There are congregations in every U.S. state, including the small community of Grand Blanc, Michigan, site of the tragic shooting. Suspect Thomas Jacob Sanford, who was fatally shot by police, had gone on a recent tirade against Latter-day Saints during a conversation with a local political candidate.

In the following days, an American member of the church raised hundreds of thousands of dollars for Sanford’s family.

Growing pains

Despite the church’s diversity, its institutional foundations remain firmly rooted in the United States. The top leadership bodies are still composed almost entirely of white men, and most are American-born.

As the church continues to grow, questions arise about how well the norms of a Utah-based church fit the realities of members in Manila or Mexico City, Bangalore or Berlin. How much room is there, even in U.S. congregations, for local cultural expressions of faith?

Latino Latter-day Saints and members in Latin America, for example, have faced pushback against cultural traditions that were seen as distinctly “not LDS,” such as making altars and giving offerings during Dia de los Muertos. In 2021, the church launched a Spanish-language campaign using Day of the Dead imagery to increase interest among Latinos. Many members were happy to see this representation. Still, some women I spoke with said that an emphasis on whiteness and American nationalism, as well as anti-immigrant rhetoric they’d heard from other members, deterred them from fully celebrating their cultures.

A couple dressed nicely and holding hands walks by a large portrait of Jesus, portrayed as a bearded white man, inside a large hallway.
People attend the twice-annual conference of The Church of Jesus Christ of Latter-day Saints on April 6, 2024, in Salt Lake City.
AP Photo/Rick Bowmer

Even aesthetic details, like musical styles, often reflect a distinctly American model. The standardized hymnal, for example, contains patriotic songs like “America the Beautiful.” This emphasis on American culture can feel especially out of sync in places in countries with high membership rates that have histories of U.S. military or political interventions.

Expectations about clothing and physical appearance, too, have prompted questions about representation, belonging and authority. It was only in 2024, for instance, that the church offered members in humid areas sleeveless versions of the sacred garments Latter-day Saints wear under clothing as a reminder of their faith.

Historically, the church viewed tattoos as taboo – a violation of the sanctity of the body. Many parts of the world have thousands of years of sacred tattooing traditions – including Oceania, which has high rates of church membership.

Change ahead?

Among many challenges, the next president of the church will navigate how to lead a global church from its American headquarters – a church that continues to be misunderstood and stereotyped, sometimes to the point of violence.

A white building in the distance, with palm trees and a clear reflecting pool in the foreground.
The temple in Laie, Hawaii, opened in the early 1900s, making it one of the church’s oldest.
Kaveh/Wikimedia Commons, CC BY-SA

The number of Latter-day Saints continues to grow in many parts of the world, but this growth brings a greater need for cultural sensitivity. The church, historically very uniform in its efforts to standardize Latter-day Saints history, art and teachings, is finding that harder to maintain when congregations span dozens of countries, languages, customs and histories.

Organizing the church like a corporation, with a top-down decision-making process, can also make it difficult to address painful racial histories and the needs of marginalized groups, like LGBTQ+ members.

The transition in leadership offers an opportunity not only for the church but for the broader public to better understand the multifaceted, global nature of Latter-day Saints’ lives today.

The Conversation

Brittany Romanello does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

ref. The new president of The Church of Jesus Christ of Latter-day Saints will inherit a global faith far more diverse than many realize – https://theconversation.com/the-new-president-of-the-church-of-jesus-christ-of-latter-day-saints-will-inherit-a-global-faith-far-more-diverse-than-many-realize-266337

Entretien avec Simon Sakaguchi, prix Nobel de médecine

Source: The Conversation – France in French (3) – By Gemma Ware, Host, The Conversation Weekly Podcast, The Conversation

Dans les années 1980, Shimon Sakaguchi, alors jeune chercheur en immunologie, peinait à obtenir des financements pour ses recherches. Aujourd’hui, ses travaux pionniers, qui ont permis de lever le voile sur la façon dont notre système immunitaire détermine à quoi s’attaquer (et à quel moment), viennent d’être récompensés par le prix Nobel de physiologie ou médecine. Dans cet entretien, il revient sur cette découverte majeure et ses implications médicales.


Le 6 octobre 2025, le Japonais Shimon Sakaguchi et les Américains Mary Brunkow et Fred Ramsdell se sont vus décerner le prix Nobel de physiologie ou médecine pour leurs travaux sur les lymphocytes T régulateurs (aussi appelés lymphocytes Treg), une classe particulière de cellules immunitaires qui empêchent notre système immunitaire de s’en prendre à notre propre corps.

Dans cet épisode du podcast The Conversation Weekly, Shimon Sakaguchi nous raconte comment il est parvenu à cette découverte, ainsi que son intérêt médical.

La transcription en francais de ce podcast est disponible en bas de cette page.


L’histoire commence par une intuition, née à la suite d’expérimentations réalisées par des collègues de Shimon Sakaguchi, au sein de l’Institut de recherche sur le cancer d’Aichi, à Nagoya. Ces derniers avaient procédé à l’ablation du thymus des souris nouvellement nées, trois jours après leur naissance. On savait déjà à cette époque que ce petit organe, situé derrière le haut du sternum chez l’être humain, jouait un rôle important dans le développement de l’autotolérance immunitaire. C’est en effet dans le thymus que les lymphocytes T qui risqueraient de s’attaquer à l’organisme sont isolés et détruits.

Si l’on retire le thymus d’une souris normale pendant la période néonatale, il semblait logique de s’attendre à ce qu’elle présente une déficience immunitaire, car ses lymphocytes auraient dû avoir disparu. Mais c’est exactement le contraire qui s’est produit chez les souris dont on avait ôté le thymus : elles ont développé des maladies auto-immunes, autrement dit des maladies au cours desquelles le système immunitaire s’en prend au corps qu’il est censé protéger. Ces maladies se sont avérées très similaires à celles observées chez l’être humain.

Ce résultat a intrigué Shimon Sakaguchi. En effet, contrairement aux souris opérées par ses collègues, les patients victimes de maladies auto-immunes possèdent toujours leur thymus. Le chercheur a alors émis l’hypothèse de l’existence d’un mécanisme commun entre les deux situations, qui expliquerait à la fois la survenue de maladies auto-immunes spontanées chez l’être humain, et le fait que des souris auxquelles on a enlevé le thymus développent néanmoins des maladies auto-immunes.

Via une nouvelle expérience, Shimon Sakaguchi a tenté d’empêcher l’emballement du système immunitaire de souris dépourvues de thymus. Pour cela, il a prélevé des lymphocytes T sur des souris génétiquement identiques aux souris opérées, et les a réinjectées à ces dernières. Ainsi traitées, les souris sans thymus ne développaient plus de maladie auto-immune. Conclusion du chercheur : « Cela suggérait qu’il devait exister une population de lymphocytes T capable d’empêcher le développement de ces maladies ».

Mais dans les années 1980, obtenir des fonds pour mener de telles recherches n’était pas chose aisée, car « la communauté des spécialistes en immunologie était très sceptique quant à l’existence de telles cellules », explique Shimon Sakaguchi. Parti pour plusieurs années aux États-Unis, le chercheur reconnaît avoir eu « beaucoup de chance » lorsqu’une fondation privée a accepté de soutenir ses travaux.

Dix ans de recherche supplémentaires ont été nécessaires avant qu’il puisse publier, en 1995, un article scientifique relatant sa découverte des lymphocytes T régulateurs. On sait aujourd’hui que ceux-ci sont en quelque sorte les agents de sécurité de l’organisme. Ils contrôlent les réactions indésirables et maintiennent l’équilibre du système immunitaire via un processus appelé tolérance périphérique. Leur dysfonctionnement peut être à l’origine de maladies auto-immunes. Les travaux ultérieurs de Shimon Sakaguchi et de ses co-récipiendaires du prix Nobel, Mary Brankow et Fred Ramsdell, ont permis de découvrir le gène Foxp3, qui contrôle spécifiquement les lymphocytes Treg.

Des maladies auto-immunes aux cancers, un fort potentiel

Au début de sa carrière,Shimon Sakaguchi s’intéressait aux maladies auto-immunes et à leurs origines. « Mais au fil de mes recherches, nous avons progressivement compris que les lymphocytes Treg constituaient un sujet plus important », souligne-t-il. On sait désormais que ces cellules sont impliquées dans la manière dont se développent les cancers, ainsi que dans la tolérance du greffon, en cas de transplantation d’organe.

Shimon Sakaguchi et ses collaborateurs travaillent également sur de nouvelles façons d’exploiter les lymphocytes Treg à des fins thérapeutiques, ainsi que sur la mise au point de protocoles permettant de convertir les lymphocytes T « auto-agressifs » en lymphocytes Treg, ce qui permettait espèrent de cibler spécifiquement les maladies auto-immunes dont ils sont responsables.

Son espoir est que, parmi les nombreux essais cliniques actuellement en cours dans le domaine de l’immunothérapie anticancéreuse en lien avec ces travaux, certains aboutissent à des solutions concrètes pour améliorer la prise en charge des patients. Il est également fasciné par de récents résultats de recherche qui suggèrent que les lymphocytes Treg seraient aussi impliqués dans les maladies liées à l’inflammation. Pour influer sur le potentiel de réparation des tissus endommagés, il pourrait être intéressant d’agir sur eux : « Les maladies neurodégénératives telles que la maladie d’Alzheimer ou la maladie de Parkinson sont associées à une inflammation. En ciblant uniquement ce type d’inflammation, nous pourrions peut-être [parvenir à] arrêter la progression de la maladie ou la retarder. Nous espérons que cette piste s’avérera réelle », conclut-il.


Cet épisode de The Conversation Weekly a été produit par Mend Mariwany et Katie Flood et est animé par Gemma Ware. Le mixage et la conception sonore ont été réalisés par Michelle Macklem et la musique du générique par Neeta Sarl.


Traduction française :


TC : Notre système immunitaire est une merveilleuse mécanique. Il est composé de nombreuses composantes qui interagissent, en particulier les anticorps et les lymphocytes T (des cellules immunitaires de type « globules blancs » qui interviennent à la fois dans la destruction des cellules infectées, la coordination de la réponse immunitaire et la mémorisation des infections). Ils nous protègent lorsque nous contractons une infection virale comme le Covid-19 ou la grippe, ou lorsque la consommation d’un curry douteux déclenche une intoxication alimentaire.

Mais chez certaines personnes, le système immunitaire dysfonctionne et s’emballe. Au lieu de cibler les bactéries ou les virus qui les menacent, il s’attaque à leur organisme, s’en prenant à leurs propres cellules. Quand cela arrive, des maladies auto-immunes peuvent se développer, telles que la polyarthrite rhumatoïde ou le diabète de type 1.

Comment notre système immunitaire sait-il contre quoi se battre, et à quel moment le faire ? Dans les années 1980, les scientifiques pensaient avoir trouvé la réponse. Ils avaient découvert que, lorsque de nouveaux lymphocytes T sont créés dans notre thymus (un petit organe situé à l’arrière de la partie supérieure du sternum), ceux qui risquent d’attaquer nos propres tissus sont éliminés. Les lymphocytes T survivants sont ensuite relâchés dans notre corps, où ils n’attaquent que les intrus. Ce concept est appelé la « tolérance au soi ».

Mais un jeune scientifique japonais, Shimon Sakaguchi, ne s’est pas satisfait de cette explication. Il a décidé de creuser davantage. Il soupçonnait que des lymphocytes T « auto-agressifs » pouvaient parvenir à s’échapper du thymus et se répandre dans l’organisme. Selon lui, un autre mécanisme existait pour faire face à ce cas de figure et contrôler lesdits lymphocytes T. Ce mécanisme fondamental aurait aussi expliqué la survenue de maladies auto-immunes spontanées chez l’être humain.

Il s’avère que Sakaguchi avait raison. En début de semaine, il a été l’un des trois scientifiques récompensés par le prix Nobel de médecine ou physiologie 2025 pour leur découverte des lymphocytes T régulateurs, appelés Treglymphocytes Treg.

Ces cellules immunitaires d’un type particulier sont en quelque sorte des gardes du corps de l’organisme ; leur rôle est d’aider à maintenir le système immunitaire en équilibre. Désormais, ces recherches alimentent des essais cliniques destinés à mettre au point des traitements pour lutter contre le cancer, le diabète, ou pour prévenir le rejet de greffes d’organes.

Je suis Gemma Ware, de The Conversation, un site d’actualité et d’analyse indépendant qui associe journalistes et universitaires. Bienvenue dans The Conversation Weekly, le podcast où des experts vous expliquent comment nous en sommes arrivés là.

TC : Shimon Sakaguchi, vous êtes professeur émérite à l’Immunology Frontier Research Centre de l’université d’Osaka au Japon et corécipiendaire du prix Nobel de physiologie ou médecine de cette année. Félicitations et bienvenue à The Conversation.

SS : Merci beaucoup.

TC : Je crois comprendre que vous étiez dans votre laboratoire lorsque vous avez reçu l’appel vous annonçant que vous aviez remporté le prix. Comment se sont passés les jours qui ont suivi ?

SK : C’était une merveilleuse surprise. J’ai ensuite reçu énormément de messages de félicitations du monde entier. C’est vraiment incroyable, et enthousiasmant.

TC : Revenons au début des années 1980. Vous travailliez alors à l’Institut de recherche sur le cancer d’Aichi, à Nagoya, au Japon. Comment en êtes-vous venu à vous intéresser au fonctionnement du système immunitaire ?
SS : J’étais très intéressé par la tolérance immunologique. Le système immunitaire nous protège des microbes qui tentent de nous envahir. Mais d’un autre côté, parfois, il se retourne contre nous et provoque des maladies auto-immunes. Donc le système immunitaire est à la fois bon et mauvais. Le fait qu’il ne s’en prenne pas à nous, c’est ce que l’on appelle la tolérance au soi. Comprendre comment cette tolérance immunitaire est établie et maintenue, constitue un des thèmes clés de la recherche en immunologie.

TC : Vous vous intéressiez à une expérience menée auparavant par certains de vos collègues sur des souris nouveau-nées. Ils avaient retiré le thymus de ces souris trois jours après leur naissance. Comme le thymus est essentiel au développement de la tolérance immunitaire (c’est d’ailleurs de là que vient le nom des « lymphocytes T », le T étant pour « thymus »), ils pensaient qu’elles auraient un système immunitaire affaibli. Mais en réalité, ce qui s’est produit, c’est que leur système immunitaire s’est emballé et que les souris ont développé des maladies auto-immunes. Qu’est-ce qui vous intriguait tant dans cette expérience ?

SS : L’expérimentation qu’ils ont menée était très intéressante. En effet, si vous enlevez le thymus de souris normales pendant la période néonatale, vous vous attendriez à ce qu’elles présentent une déficience immunitaire puisqu’elles n’ont alors plus de lymphocytes. Mais il s’est passé tout le contraire : elles ont développé des maladies auto-immunes. Des maladies très similaires à celles que l’on observe chez l’être humain. Il se passait donc là quelque chose d’intéressant. Évidemment, chez les patients humains [qui développent des maladies auto-immunes], le thymus n’a pas été retiré. Il devait donc exister un mécanisme commun capable d’expliquer [le résultat observé chez les souris ayant subi une ablation du thymus] et les maladies auto-immunes spontanées chez l’humain.

TC : Vous avez alors décidé d’une autre approche, pour voir si vous pouviez empêcher le système immunitaire des souris sans thymus de s’emballer. Vous avez prélevé des lymphocytes T sur des souris génétiquement identiques et les avez introduits dans l’organisme de celles auxquelles on avait enlevé le thymus. Qu’avez-vous découvert ?

**SS : **C’est tout à fait cela, et de cette façon, la survenue de maladies a pu être prévenue. Cela suggérait donc qu’il devait exister une population de lymphocytes T capable d’empêcher le développement des maladies [auto-immunes]. Une sorte de population « suppressive ».

TC : Racontez-nous ce moment où vous avez réalisé que les souris allaient bien et que vous aviez réussi à les protéger des maladies auto-immunes. Qu’avez-vous ressenti ?

SS : De l’excitation, et le sentiment qu’il s’agissait de quelque chose d’important. Puis que si nous analysions plus en profondeur ce phénomène, il pourrait peut-être nous apprendre un principe immunologique fondamental à propos de la tolérance. Je me disais que si je pouvais découvrir cela, disons, dans les dix ans, ce serait formidable. C’est là tout ce que j’espérais à cette époque.

TC : Aviez-vous conscience à ce moment-là d’avoir fait une grande découverte ?

SS : Une grande découverte ? Disons que dans le domaine de l’immunologie, c’était certainement quelque chose, car c’était essentiel pour comprendre les maladies immunologiques. Quant à savoir si c’était une « grande découverte » ou non… Cela allait dépendre de notre capacité à démontrer que nous pouvions guérir de telles maladies ou en empêcher le développement. À cette époque, il restait encore à savoir comment nous allions pouvoir généraliser ce que nous avions trouvé.

TC : Avez-vous rencontré des difficultés, dans les années 1980, pour poursuivre ces travaux de recherche ?

SS : Il n’a pas été facile d’obtenir des financements, car la communauté des spécialistes en immunologie était très sceptique quant à l’existence de tels lymphocytes. Mais à cette période, j’ai passé près de dix ans aux États-Unis, où j’ai eu beaucoup de chance, car une fondation privée, la Lucille P. Markey Foundation, a soutenu mes recherches pendant huit ans. Le soutien de jeunes chercheurs par des fondations privées était bien plus courant aux États-Unis qu’au Japon. J’espère que ce type de pratique ou de système se poursuivra, non seulement aux États-Unis, mais aussi au Japon.

TC : Vous aviez donc mené cette expérience sur des souris et réalisé qu’il existait un type particulier de lymphocyte T. Mais comprendre plus précisément de quoi il retournait vous a pris environ une décennie. Une fois que vous y êtes parvenu, vous avez baptisé ces lymphocytes T des lymphocytes T régulateurs, ou lymphocytes Treg. Il s’agit donc d’un type particulier de lymphocytes T, qui empêchent notre système immunitaire de surréagir et d’attaquer notre corps. Vous avez publié votre article sur les lymphocytes T régulateurs en 1995. Comment a-t-il été reçu à l’époque ?

SS : Avant cette date, les gens considéraient qu’il s’agissait d’un phénomène intéressant. Mais ce n’est que lorsque nous sommes parvenus à définir cette population grâce à un marqueur spécifique que tout le monde a pu observer les mêmes cellules que nous. Avant cela, les autres chercheurs ne pouvaient pas vérifier que ce que nous affirmions était vrai. Nous avons démontré que ces lymphocytes étaient exprimés fortement, et de façon constitutive. Chacun a ensuite pu reproduire nos expériences et le confirmer.

TC : En gros, ces lymphocytes T régulateurs que vous aviez identifiés circulent et empêchent tout lymphocyte T agressif qui se serait échappé du thymus d’attaquer notre corps. Si nous n’en possédons pas, nous risquons de développer une maladie auto-immune. Mais aujourd’hui, nous savons aussi que le rôle joué par les lymphocytes Treg est beaucoup plus large que cela. Pourquoi est-ce si important ?

SS : J’avais un intérêt pour les maladies auto-immunes, et leurs origines. C’était ce qui motivait mes recherches, ce qui en constituait la force directrice. Mais au fil de mes travaux, j’ai compris que les lymphocytes Treg étaient importants non seulement en matière de maladies auto-immunes, mais aussi pour l’immunité tumorale, la tolérance vis-à-vis des greffons, et plus récemment, la réparation des tissus. Ils ont donc de multiples fonctions. Tout ça est aujourd’hui très enthousiasmant.

TC : Revenons à l’époque où vous identifiiez ces lymphocytes T régulateurs. Vos collègues et corécipiendaires du Nobel, Mary Bruncko et Fred Ramsdell, travaillaient aux États-Unis à comprendre les gènes derrière une maladie auto-immune rare et invalidante. Dans le cadre de ces travaux, ils ont découvert le gène qui contrôle le fonctionnement des lymphocytes T régulateurs. Vous souvenez-vous de la publication de leur article en 2001 ? Quelle a été votre réaction ?

SS : Nous avions remarqué cet article. Un gène avait été identifié et une anomalie ou mutation de ce gène provoquait non seulement des maladies auto-immunes, mais aussi des allergies et des maladies inflammatoires chroniques de l’intestin. Donc un seul gène était responsable de multiples pathologies immunologiques. Ledit gène avait été découvert, mais les auteurs n’avaient pas montré comment cette anomalie génétique entraînait ces maladies immunologiques.

Nous avons immédiatement commencé nos recherches sur ce gène, appelé FoxP3. Nous avons postulé que ce gène devait être lié à la fonction ou au développement des Treg. Nous avons donc commencé diverses expérimentations, et publié nos résultats deux ans plus tard : nous avons démontré que ce gène était spécifique des lymphocytes T régulateurs.

TC : Les connaissiez-vous personnellement ? Étiez-vous en contact avec eux, scientifiquement parlant ?

SS : Non, je ne les connaissais pas à l’époque. Mais bien sûr, nous nous sommes rencontrés lors de congrès scientifiques, en particulier Fred Ramsdell. Ils avaient publié leurs découvertes et les présentaient également dans des colloques.

TC : Nous commençons seulement à comprendre ce que vos découvertes pourraient apporter en matière d’amélioration de la santé. Quelles sont, selon vous, les pistes de recherche les plus prometteuses et sur quoi travaillez-vous actuellement ?

SS : Les Treg sont spécialisées dans la suppression immunitaire. Cela signifie qu’en les renforçant ou en les multipliant, elles pourraient être utilisées pour traiter des maladies immunologiques, notamment les maladies auto-immunes, les allergies ou le syndrome de l’intestin irritable.

Ce qui est enthousiasmant, c’est que plus de 200 essais cliniques sont en cours : on prélève chez les patients des Treg naturellement présents dans leur organisme, on les multiplie puis et on les leur réinjecte.

Mais nous menons aussi des projets plus ambitieux : nous essayons de convertir des lymphocytes T effecteurs ou mémoires spécifiques d’une maladie — donc des « mauvais » lymphocytes — en Treg. Nous espérons de cette façon aboutir à une suppression spécifique d’un antigène ou d’une maladie (le terme « antigène » désigne tout élément étranger à l’organisme capable de déclencher une réponse immunitaire, ndlr).

TC : Ces « mauvais » lymphocytes T qui attaquent l’organisme, vous voulez les transformer en Treg pour qu’ils deviennent des gardes du corps ?
SS : Exactement. C’est ce que nous poursuivons actuellement.

TC : Quelles maladies ciblez-vous ?

SS : Diverses maladies auto-immunes, par exemple des maladies auto-immunes du foie, dont l’hépatite auto-immune, pour laquelle le seul traitement actuellement disponible est la corticothérapie (traitement par corticostéroïdes).

TC : D’autres équipes s’intéressent aussi au cancer. Pouvez-vous expliquer comment cela fonctionnerait ?

SS : C’est un autre espoir en matière de recherche sur les lymphocytes Treg. Ces derniers sont abondants et très fortement activés dans les tissus cancéreux. La réponse immunitaire dirigée contre les cellules cancéreuses est de ce fait inhibée.

L’idée est de trouver une façon de réduire la quantité de Treg et ainsi améliorer la réponse immunitaire antitumorale. Nous espérons à terme parvenir à développer une petite molécule administrable par voie orale qui serait capable de renforcer ladite réponse en faisant diminuer le nombre de lymphocytes Treg présents dans les tissus tumoraux. Nous sommes encore loin de l’objectif, mais ce type de recherche nous intéresse au plus haut point.

TC : En lisant vos travaux, on se rend compte à quel point ils s’appuient sur les recherches de ceux qui vous ont précédé, non seulement au sein de votre propre laboratoire, mais aussi ceux qui ont œuvré durant les décennies précédentes, et qui pour certains ont aussi obtenu un prix Nobel. Qu’aimeriez-vous que l’on fasse de vos découvertes à l’avenir ?

SS : Eh bien, mon espoir immédiat est que les Treg deviennent un outil efficace pour traiter diverses maladies immunologiques, ou que l’on parvienne à les cibler dans le cadre d’immunothérapies anticancéreuses. J’espère que cela deviendra très prochainement une réalité clinique. Dans le même temps, des recherches récentes ont montré que ces lymphocytes ont aussi d’autres fonctions, en plus de leur rôle immunosuppresseur.

Concrètement, cela signifie qu’ils pourraient présenter un intérêt au-delà des maladies immunologiques, notamment dans le traitement de maladies neurodégénératives telles que les maladies d’Alzheimer ou de Parkinson, dans lesquelles l’inflammation joue un rôle. En ciblant cette inflammation, nous pourrions peut-être ralentir leur progression.

C’est une piste très intéressante, nous espérons qu’elle se confirmera, et que cette approche pourra fonctionner pour ce type de pathologies.

The Conversation

Shimon Sakaguchi est le fondateur scientifique et directeur de RegCell, une start-up japonaise qui travaille sur des traitements basés sur les lymphocytes T régulateurs. Il est également conseiller scientifique pour la société de biotechnologie Coya Therapeutics. Il a reçu des financements de l’Agence japonaise pour la recherche et le développement médicaux, de la Société japonaise pour la promotion de la science et pour des recherches collaboratives avec CHUGAI PHARMACEUTICAL, Otsuka Pharmaceutical et RegCell.

ref. Entretien avec Simon Sakaguchi, prix Nobel de médecine – https://theconversation.com/entretien-avec-simon-sakaguchi-prix-nobel-de-medecine-267233

Political violence: What can happen when First Amendment free speech meets Second Amendment gun rights

Source: The Conversation – USA – By Gregory P. Magarian, Thomas and Karole Green Professor of Law, Washington University in St. Louis

The proliferation of guns in the U.S. can elevate political rhetoric to political violence. Douglas Sacha, Moment/Getty Images

The assassination in September 2025 of conservative activist Charlie Kirk has heightened attention on the relationship between political rhetoric and political violence.

Even before police had identified a suspect, President Donald Trump blamed the shooting on the “rhetoric” of the “radical left.” The Trump administration has since acted to silence left-leaning speakers and is threatening to intensify its attacks on left-wing political speech.

But my decades of studying free speech law have convinced me that suppressing political rhetoric, even through social norms rather than law, undermines the discussion, debate and constructive disagreement essential for a healthy democracy.

Gun proliferation complicates the problem by making political violence much easier to carry out.

Rise of political violence

Political violence – by which I mean any physical attack on people that aims to achieve a political goal – harms democracy by shifting the field of political disagreement from debate to aggression.

Under the U.S. constitutional system of limited government and individual rights, political violence by the government – for example, government assaults on anti-government protesters – is among the gravest threats to liberty.

But political violence committed by private individuals or groups also corrodes constitutional democracy. In the United States, acts of private political violence against members of government and against ordinary people have both increased dramatically in recent years.

Political assassinations are the most vivid form of political violence. The Kirk assassination is only the latest example.

An attendee wears a gun on their hip during a candlelight vigil and prayer event at which an American flag is displayed.
An attendee at a candlelight vigil and prayer event for assassinated Turning Point USA Founder Charlie Kirk on Sept. 10, 2025, in Seattle.
David Ryder/Getty Images

In June 2025, a shooter with a “hit list” of left-liberal targets assassinated Minnesota Democratic Rep. Melissa Hortman and her husband. In December 2024, a shooter angry about health insurance costs killed United Healthcare CEO Brian Thompson. In July 2024, a shooter wounded Trump at a campaign rally in a failed assassination attempt.

Political violence also includes bias-motivated murders. In 2022, a white supremacist murdered 10 Black patrons at a grocery store in Buffalo, N.Y. In 2019, an anti-immigrant racist murdered 23 mostly Latino shoppers at a Wal-Mart in El Paso, Texas. In 2018, an antisemite murdered 11 congregants at a Pittsburgh synagogue.

In those incidents and numerous others, extreme political ideas appear to have motivated the attackers. The linkage of extremist speech to lethal violence has prompted calls to legally restrict or punish extremist speech.

Political violence, free speech and cultural editing

The First Amendment, however, protects extremist speech, including advocacy of violence. Violent rhetoric must actually incite or threaten violence to lose the First Amendment’s shelter.

If law cannot curb the sorts of speech that may inspire political violence, what about social norms – widely shared beliefs about what speech is socially acceptable or appropriate?

Much speech that the First Amendment protects from government regulation eventually disappears from public discourse. That happens through a process I call “cultural editing”: popular and institutional rejection of outmoded or repellent ideas. For example, no serious medical conference discusses treating hay fever with cocaine, and no respectable political science panel includes Nazis.

In a social media post after Charlie Kirk’s killing, President Donald Trump blamed ‘radical left’ rhetoric for political violence.

The Trump administration’s blaming of the Kirk assassination on “radical left” rhetoric points toward a deeper level of cultural editing.

Trump and other conservatives have not cited speech that advocated violence against Kirk. Instead, some conservative activists, spurred on by Trump administration officials, called for harassing and punishing critics of Kirk’s statements and actions.

But such criticisms of Kirk, whatever their merits or lack thereof, fall within the scope of ordinary political debate.

Kirk was not a government official, but he had strong influence in the Trump administration. Robust democratic discourse requires space for people to criticize such powerful figures. Large-scale cultural editing of those criticisms, amounting to suppression of left-leaning views, would hurt the public’s ability to discuss and resolve political disagreements.

However, Trump and others who push for suppressing harsh political rhetoric might argue that the stakes of verbal attacks have increased. They might say that U.S. political culture can no longer indulge political invective because political violence has become more common.

Political violence and guns

That argument for suppressing harsh political speech ignores an independent cause of political violence: gun proliferation.

Most political violence in the U.S. involves guns. Guns make political violence easier by erasing the distance between extremist ideas and lethal action. Hate or fanaticism can end a life in an instant, hundreds of yards from the victim.

The U.S. has by far the highest number of civilian guns and rate of civilian gun ownership in the world. Since 2008, when the Supreme Court declared an individual Second Amendment right to keep and bear arms, annual U.S. gun purchases have increased from about 9 million to about 16 million.

Governments often find regulating speech easier, even though less effective, than tackling underlying problems. At times, federal and state governments have addressed political violence by regulating guns. The 1994 federal assault weapons ban exemplifies regulatory efforts to curb overall gun violence.

But the Supreme Court’s Second Amendment cases now appear to bar strong gun regulations.

People in a democratic society need freedom to make harsh, even extreme political statements with a minimum of cultural editing. The Second Amendment protects access to lethal weapons. This combination of free speech and gun rights makes the growing problem of political violence much harder to solve.

The Conversation

Gregory P. Magarian does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

ref. Political violence: What can happen when First Amendment free speech meets Second Amendment gun rights – https://theconversation.com/political-violence-what-can-happen-when-first-amendment-free-speech-meets-second-amendment-gun-rights-265223

Kerouac’s Road: The Beat of A Nation – this documentary can’t reconcile nostalgia with the true contemporary US

Source: The Conversation – UK – By Michael Collins, Reader in American Studies and Chair of The British Association for American Studies, King’s College London

When Jack Kerouac published On the Road in 1957, he presented the novel as the product of a single marathon writing binge. It was a method he had been working on since the late 1940s that his friend Allen Ginsberg dubbed “spontaneous bop prosody”.

Despite the manuscript actually being a synthesis of years of ten years of notes and fragments (as this film shows), the press went mad for the myth of spontaneous prose. What could be more exciting at the height of the cold war than presenting the US as the place of ultimate freedom and possibility, something apparently unavailable to non-western or socialist nations?

On the Road seemed to be an organic, undiluted product of America. It poured out raw and thick from the mind of a man whose voice was marketed as a synthesis of the repressed forces that lay buried beneath the veneer of American postwar prosperity. The US “culture industry” burned heavy diesel in the promotion of Kerouac.

There were naysayers. Other writers like Truman Capote loathed the book. Of the Beat generation in general he once quipped: “None of them can write, not even Mr Kerouac … [it] isn’t writing at all – it’s typing”.

There were also many conservative critics that denounced the work’s sexual morality. But here was the cleverness of the “culture industry”. These critics could be rendered as an older cultural elite unable to grasp the significance of the novel. Or even as dried-up husks of an obsolescent religious right. This was the late fifties; a new world was coming. Better get off the freeway if you can’t stand the speed.

The trailer for Kerouac’s Road: The Beat of A Nation.

However much his fans might cling to this vision of the novel, Kerouac does not have the reputation now he did in the 1960s and 1970s. Waves of feminist criticism, ecological theory and a more cautious stance in literary culture toward the American political project have left him something of a fossil.

It is intriguing, therefore, to see the director of Kerouac’s Road, Ebs Burnough (former deputy social secretary to the Obama White House), return to this mythologisation of the American open road. Does something of Kerouac’s Americana still exist, the film asks, in the era of Black Lives Matter (BLM), of militarised police, at a time when those conservatives who were once so easy to denounce have taken control of the public discourse?

Burnough’s film attempts to synthesise two competing narratives that do not quite hold together. First, it’s a strong (if not wholly original) account of the reception of Kerouac’s novel and the author himself. It uses interviews with celebrity fans, the American writer Joyce Johnson (a former girlfriend of Kerouac’s who has superb things to say about life for the “Beat” women) and Kerouac’s biographer Ann Charters.

Second, the director interweaves three micro-narratives of contemporary American road trips that have some rather loose relationship to the ideas of freedom Kerouac is held to represent. One follows a young Black man from Philadelphia who is in the process of leaving the poverty of his home city for the promises of Morehouse University (the reverse narrative of Kerouac who dropped out of Columbia). Another is a couple who are living on the road to re-energise their marriage. Another shows a woman’s reunion with her abusive father.

The principal issue is that the film cannot reconcile its nostalgia for Kerouac’s era with the true historical and political conditions of the contemporary US.

For one, Kerouac’s novel is anything but an account of American plurality. On the Road has a relentlessly over-determined first-person voice that is notable for its blind spots far more than the truly expansive panoramic vision of American life Burnough takes to it be.

To its credit, the film does address the fact that really, at core, On the Road is about one man’s (the narrator Sal Paradise) obsession with another (Dean Moriarty). Yet there is nothing much here about the irony that the very obsession with unfiltered first-person speech, which Kerouac’s novel made so fashionable in American literature, has since toxified. It is now associated with masculine “free speech” and the suppression of alternatives that define contemporary political discourse.

Today, Sal Paradise would have a podcast. And I am not convinced, swathed in deep misogyny and violence as the novel is, that it would be much different from some of the worst of the manosphere.

On The Road is an exercise in resource extraction (of people, especially women, fuel and landscape, seen as salve to the troubled male soul). This is what makes it interesting as a cultural account of the 1950s. In the film, only the singer-songwriter Natalie Merchant (who is predictably brilliant, insightful and wise) and the comic and cultural critic W. Kamau Bell come close to seeing this.

The Trayvon generation

At 25 minutes in the director overdubs Joyce Johnson speaking about the Beat generation as the voice of the underclass of the 1950s on to an image of Amin (the Morehouse student) wearing a BLM hoodie.

It is hard to know if the director is being ironic, or if what the poet Elizabeth Alexander has called “the Trayvon generation” (after Trayvon Martin, the 17-year-old African-American boy who was fatally shot by his neighbour in 2012) is meant to be seen as a Beat generation in utero. The chasm economically and socially between the conditions of the later 1940s-50s and the present day make this parallel seem highly dubious. Most Black men in the contemporary US would not risk crossing the country at 70mph while drinking and driving a Chevy, as Sal Paradise does in On the Road.

The film does address the pervasive culture of violence in contemporary America at moments. One of most poignant interviews is with Amin’s mother who is worried about her son being shot. Yet, the film does not suggest this could be the responsibility of the police. The fault, it seems to imply, lies within the community. This is an egregious misrepresentation of the purpose of BLM, and seems at best politically muted from the director.

The film is very unwilling to undertake the critique needed to measure the distance between the Beats and Trump’s America. Indeed, it actually reproduces many of the flaws of Kerouac himself in being so optimistic about the US. The problems of the world today are not solved by a road-trip anymore than they were in 1957.


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The Conversation

Michael Collins does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

ref. Kerouac’s Road: The Beat of A Nation – this documentary can’t reconcile nostalgia with the true contemporary US – https://theconversation.com/kerouacs-road-the-beat-of-a-nation-this-documentary-cant-reconcile-nostalgia-with-the-true-contemporary-us-267030

Should you be concerned about ‘overspending’ your daily heart beats?

Source: The Conversation – UK – By Tom Brownlee, Associate Professor, Sport and Exercise Science, University of Birmingham

fizkes/Shutterstock.com

Imagine if your smartwatch didn’t just tell you how many steps you’ve walked or calories you’ve burned, but how many heartbeats you’ve “spent” each day. According to a recent study, that number might one day become another marker of health – a “heartbeat budget” that could, in theory, tell you if you’re overspending your most vital resource.

The idea of a lifetime heartbeat limit has floated around for decades. It’s based on an old myth that the heart comes with a fixed number of beats, often said to be about 2.5 billion, so every extra one you use brings you closer to running out. Thankfully, that’s pretty roundly accepted now to be untrue.

Exercise doesn’t shorten your life by making your heart beat faster. If anything, people who exercise tend to have lower resting heart rates and live longer. But the new research, published in JACC: Advances, borrows that same metaphor in a modern, data-driven way.

The scientists behind the study analysed fitness-app data from elite athletes, comparing resting heart rates with total daily beats. They estimated that endurance-trained athletes “save” around 11,500 heartbeats per day compared with untrained adults, thanks to lower resting rates.

But those savings don’t last. A single Tour de France stage can cost riders about 35,000 extra beats – according to the researchers’ estimates – reflecting just how hard the heart works during a competition.

This push and pull, saving beats at rest, spending them during exertion, is what researchers call heartbeat consumption. The concept is simple: your total beats per day reflect how your heart responds to everything you do, from sleep to stress to sport. Fitness trackers already measure heart rate continuously, so it wouldn’t take much to start summing those beats and turning them into a new health metric.

But does it actually mean anything? That’s where things get murkier. The study’s authors admit their analysis was small and observational. They didn’t track participants’ health outcomes, only patterns in their heart rate data. A high daily heartbeat count could mean someone is active, or it could reflect anxiety, poor fitness, caffeine or heat. Without context, the number itself tells us little.

One hand on a keyboard, the other on a mug of coffee.
A high daily heart beat count might just mean you’ve had too much coffee.
Anastasiia Bevziuk/Shutterstock.com

Still, the idea has intuitive appeal. Heart rate is one of the clearest windows into how our body is coping with life’s demands. A persistently high resting heart rate has been linked to an increased risk of heart disease, stroke and early death.

Meanwhile, variability in the timing between beats, known as heart rate variability, is a well-established indicator of stress and emotional wellbeing. Thinking in terms of “beat consumption” could help people visualise that connection between physical and mental load.

Athletes already know the power of that balance. Training too hard, too often, can elevate resting heart rate, reduce heart rate variability and blunt performance – a classic sign of overtraining.

Lighter, so-called active recovery sessions, where the heart rate stays low, are known to speed recovery, improve overall performance and stabilise mood. If a “heartbeat budget” helps people notice when their ticker is working overtime, it might encourage gentler activity days before burnout hits.

What the data doen’t tell us

There are also implications for people living with chronic conditions. Some health apps already use heart rate thresholds to help users avoid overexertion, especially when fatigue or heart strain can make recovery costly. In that sense, tracking heartbeat consumption could serve as a safety signal rather than a competition, a way of knowing when the body needs to slow down.

But as with most bright new ideas in fitness science, a note of caution is needed. The JACC authors acknowledge that they used fitness tracker data from a small sample of highly trained cyclists and runners. That’s a narrow slice of the population.

They didn’t measure blood pressure, oxygen levels or recovery biomarkers – all of which matter for heart health. Translating those findings into advice for ordinary smartwatch users will take larger, long-term studies.

Then there’s the philosophical question: should we really treat heartbeats as a finite commodity? Exercise “spends” heartbeats in the short term but often “earns” more life in the long run.

A long-distance runner’s heart might beat more times in a single day, but fewer times across a lifetime, because endurance training lowers resting rate and improves cardiac efficiency. In that sense, using your heart isn’t the problem, but not using it might be.

Heartbeat consumption, at least for now, remains a metaphor in search of meaning. Still, it’s a poetic one. Whether or not your fitness tracker or smartwatch ever starts counting total beats, the message behind it is simple: pay attention to how your heart behaves across the day. It’s not about saving beats – it’s about spending them wisely.

The Conversation

Tom Brownlee does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

ref. Should you be concerned about ‘overspending’ your daily heart beats? – https://theconversation.com/should-you-be-concerned-about-overspending-your-daily-heart-beats-266829

Why do so many female animals live longer than males? New research

Source: The Conversation – UK – By Rob Salguero-Gomez, Professor of Ecology, University of Oxford

Female chimpanzees live for longer than their male counterparts. jindrich_pavelka/Shutterstock

I’ve long been fascinated by one of the most stubborn patterns in biology: males and females rarely live the same length of time. In humans, women nearly always outlive men, with an average advantage of about five years worldwide today. This pattern holds across history, from 18th-century Swedes to contemporary Japanese – though the magnitude of this sex-difference can vary considerably.

Humans are not alone in showing such sex biases in longevity. Across the Tree of Life, sex differences in longevity are widespread, but they are neither uniform nor always female-biased.

And a new study study led by evolution researcher Johanna Staerk, published in Science Advances, conducted the most comprehensive analysis of sex differences in longevity in birds and mammals. The study offered new insight into why these differences evolved and found these differences are more pronounced in the wild than in zoos.

Among mammals, females generally live longer. The recent comparative study examined 528 mammal species in zoos and found that 72% showed a female life expectancy advantage, averaging 12% longer lives for females. In the wild, where environmental pressures are stronger, the female advantage was even greater: around 19%.

In my own work with the Compadre animal demographic database and with wild populations, I’ve seen the same female advantage emerge time and again. Wild female African elephants often live into their 60s, while males rarely exceed their late 40s. This is in part because males spend much of adulthood in risky solitary ranging and competing through combat. Similarly, in moose, females live twice as long (17-22 years) as males.

Genetics plays a key role. Male mammals are the heterogametic sex (meaning males have an X and a Y sex chromosome), so males are more likely to inherit recessive x mutations. Also high levels of testosterone can suppress immune function.

However, the clearest evidence points to sexual selection. In polygynous mammals (males compete for access to harems of females) such as red deer or lions, males grow large bodies and weaponry, and fight for mates, which reduces their survival chances.

Close up of stag against sunset.
Those magnificent antlers come with a cost.
HMD_93/Shutterstock

Birds: the male advantage

The reversal in birds still surprises students when I teach life-history theory. Biology rarely hands us neat rules.

Across the 648 avian species studied in zoos by Staerk and colleagues, in 68% of them males outlived females, with an average 5% male advantage. In the wild, the gap widened to over 25%.

Female birds are the heterogametic sex (ZW chromosomes), which may expose them to greater genetic risks. More importantly, many female birds pay heavy reproductive costs. Egg production, incubation and chick rearing demand enormous energy. In some species such as ducks and songbirds, this burden translates into shorter female lifespans.

The exceptions are illuminating. Raptors like buzzards and eagles often show a female advantage. In the wild, female tawny owls live longer. But in zoos the advantage shifts to males. The reason is not yet known.

Beyond fur and feathers

Previous research has shown insects have vivid contrasts in longevity. In many moths and mayflies, females live only a few hours or days as adults, exhausting themselves in egg laying, while males persist days or weeks longer. Insects who live in highly organised colonies reverse this pattern: ant and bee queens can live decades, far outlasting short-lived male drones.

Here, the colony shields queens from many ecological risks, such as the need to evade predators when out looking for food, illustrating how social organisation can radically alter the relationship between sex and survival.

Amphibians and reptiles are known to showcase mixed patterns. Male frogs often die younger due to the costs of calling and combat at breeding sites, whereas female frogs sometimes pay higher survival costs through egg production.

Fish often show flexibility in sex roles, alongside variability in female and male lifespans. In stickleback fish, males provide sole parental care, defending nests at great cost. They often die shortly after the breeding season, while females survive to reproduce again. Conversely, in species where females produce enormous clutches, their shorter lives balance the equation.

Humans in context

Across cultures and history, women live longer than men. In 21st-century Japan, female life expectancy exceeds 87 years, compared to 81 for men. Among Hadza hunter–gatherers, who live in Tanzania, women live longer than men too.

Social and medical advances, such as better maternal care, have widened the human female edge in modern populations.

Intriguingly, the human “female advantage” is smaller than in apes, probably because sexual selection is weaker in humans. Female chimpanzees and gorillas live substantially longer than males, often by more than a decade. Indeed, men face fewer risks from mate competition than chimpanzees.

Why does sex-based longevity differ so much?

There are two main hypotheses. First is the heterogametic sex hypothesis, as mentioned above, which predicts that the sex with two different sex chromosomes (XY in mammals, ZW in birds) suffers shorter lives. However, this fails to explain the exceptions, such as long-lived female raptors.

Second are life history and sexual selection trade-offs. Traits that increase reproductive success often reduce survival. Among mammals, males die younger when they invest heavily in competition, size or weaponry. Among birds, females pay with their lives for egg production and parental care. The new study supported this explanation. Non-monogamous mammals with significantly larger males show the largest female advantage.

Who wants to live forever anyway

A longer life does not necessarily translate into better quality of life. In humans, although women live longer almost everywhere, they often spend more years in poor health compared to men, burdened by chronic conditions such as osteoporosis, dementia or autoimmune disorders. Similarly, in some nonhuman animals, females survive longer but may experience prolonged periods of reduced reproduction or physical performance.

A “female advantage” in survival may therefore come with hidden costs.

So, do females live longer than males across the Tree of Life? Often, yes, but not because of a universal law. The patterns are the messy product of chromosomes, hormones, competition, care and chance. That’s what makes it such an interesting question to study.

The Conversation

Rob Salguero-Gomez receives funding from NERC.

ref. Why do so many female animals live longer than males? New research – https://theconversation.com/why-do-so-many-female-animals-live-longer-than-males-new-research-266824

It’s not screen time that matters, it’s what you do and when you do it – new study

Source: The Conversation – UK – By Daniel Joinson, PhD Candidate, Engineering and Maths, University of Bristol

Olezzo/Shutterstock.com

What if the problem with social media isn’t just how much we use it, but when? A new study suggests that scrolling and posting through the small hours may be a red flag for mental wellbeing – and the effects could be as significant as binge drinking.

For the study, published in Scientific Reports, my colleagues and I analysed the Twitter (now X) habits of 310 adults and discovered that those who regularly posted between 11pm and 5am showed meaningfully worse mental wellbeing than daytime users. This finding challenges the current policy obsession with screen time limits and points toward a more nuanced understanding of how social media affects our mental health.

Australia has passed a law to ban social media for anyone under 16, with 68% of the population supporting the new law. Similar proposals are being debated across the western world, where policymakers cite rising concern about youth mental health. But is the solution that simple? Science tells a more complicated tale.

Studies examining social media use have found associations with worse mental health, better mental health and even no change at all. And a large analysis of over 350,000 people found that while more time on social media was associated with poorer mental health, the effect was minuscule.

The trouble with this research is its fixation on amounts of time spent on social media. Two people might spend identical amounts of time on social media yet have completely different experiences – one scrolling passively, the other engaged in fraught late-night exchanges. The difference in behaviour matters, and so does the platform where it occurs.

Complete bans will eliminate harmful effects, but they also remove potential benefits. Many young people rely on these platforms to form and maintain friendships. For those already struggling mentally, social media can provide support, guidance and community that might otherwise remain out of reach.

On the other hand, late-night use could push back bedtimes, fracture sleep quality and consequently harm mental health. The harm may intensify with highly interactive activities – posting, messaging – compared with passive browsing.

Understanding what people do on social media – and crucially, when they do it – is essential to grasping its real effect.

A phone screen showing a number of different social media apps.
The harms depend on what you do online.
aileenchik / Shutterstock.com

The night shift: what we found

Our study explored this using real-world Twitter data from participants in the Avon Longitudinal Study of Parents and Children, matched with detailed self-reported mental health measures. These include the Warwick-Edinburgh Mental Wellbeing Scale – a 14-item measure of how someone feels and functions. We produced statistical models, aiming to predict these measures of mental health from the average time of day our participants posted their tweets.

We found strong evidence that the time someone posts on Twitter was associated with their mental wellbeing. Posting time accounted for about 2% of the differences in wellbeing between participants. This may sound small, but it’s a similar effect size to that found for binge drinking in other research.

Regular nighttime tweeters (23:00 to 05:00) consistently reported worse mental wellbeing than those posting primarily during daylight hours.

We also looked at how posting times related to symptoms of depression and anxiety. While mental wellbeing captures the positive side of mental health, depression and anxiety reflect specific problems that can undermine it.

The links between posting time and these symptoms were weaker overall, but they varied by age and sex. For example, the relationship between posting time and anxiety was about twice as strong in older participants, with posting time explaining 1.3% of the differences in anxiety levels among older users compared with 0.6% among younger ones.

Critical questions remain. Are we witnessing the harmful consequences of late-night posting, or do people with worse mental health gravitate toward nighttime social media use? Do these patterns translate to other platforms or different demographics, particularly adolescents and children?

If nighttime social media use genuinely harms mental health, then targeted solutions could be valuable. TikTok recently launched “wind down”, which replaces the homepage for under-16s with calming music and breathing exercises after 10pm. And in the UK, the government is now considering legislation to restrict multiple platforms after 10pm for this age group.

Nighttime use demonstrates how policy and platforms can address potentially harmful behaviour without resorting to outright bans. It represents a shift away from crude measurements of screen time toward considering what people do, when and where they do it, and who they are.

This approach moves us beyond simple measurements, toward a better understanding of how our digital lives affect our mental health.

The Conversation

Daniel Joinson receives funding from the EPSRC (grant number EP/S023704/1)

ref. It’s not screen time that matters, it’s what you do and when you do it – new study – https://theconversation.com/its-not-screen-time-that-matters-its-what-you-do-and-when-you-do-it-new-study-266845