Category: English

Source: The Conversation – USA (2) – By Sarah Porter, Director of the Kyl Center for Water Policy, ASU Morrison Institute for Public Policy, Arizona State University

The Colorado River is in trouble: Not as much water flows into the river as people are entitled to take out of it. A new idea might change that, but complicated political and practical negotiations stand in the way.

The river and its tributaries provide water for about 5 million acres of cropland and pasture, hydroelectric power for millions of people, recreation in the Grand Canyon, and critical habitat for fish and other wildlife. Thirty federally recognized Native American tribes assert rights to water from the Colorado River system. It is also an important source of drinking water for cities within the Colorado River Basin, including Phoenix, Tucson and Las Vegas, and cities outside the basin, such as Los Angeles, San Diego, Salt Lake City, Denver and Albuquerque.

The seven Colorado Basin states have been grappling with how to deal with declining Colorado River supplies for a quarter century, revising usage guidelines and taking additional measures as drought has persisted and reservoir levels have continued to decline. The current guidelines will expire in late 2026, and talks on new guidelines have been stalled because the states can’t agree on how to avoid a future crisis.

In June 2025, Arizona suggested a new approach that would, for the first time, base the amount of water available on the river’s actual flows, rather than on reservoir level projections or historic apportionments. While the proposal has been praised as offering “a glimmer of hope,” coming to agreement on the details presents daunting challenges for the Colorado Basin.

The Colorado River Compact

The 1922 Colorado Compact divided the 250,000-square-mile Colorado River Basin into an Upper Basin – which includes parts of Colorado, New Mexico, Utah and Wyoming, as well as the northeastern corner of Arizona – and a Lower Basin, encompassing most of Arizona and parts of California and Nevada. The compact apportions each basin 7.5 million acre-feet of water from the river each year. An acre-foot of water is enough to cover 1 acre in water 1 foot deep, which amounts to approximately 326,000 gallons. According to a 2021 estimate from the Arizona Department of Water Resources, 1 acre-foot is sufficient to supply 3.5 single-family households in Arizona for one year.

Anticipating a future treaty with Mexico for sharing Colorado River water, the compact specified that Mexico should be supplied first with any surplus available and any additional amount needed “borne equally” by the two divisions. A 1944 water-sharing treaty between Mexico and the U.S. guarantees Mexico at least 1.5 million acre-feet of Colorado River water annually.

The compact also specified that the Upper Basin states of Colorado, New Mexico, Utah and Wyoming “will not cause the flow of the river … to be depleted below an aggregate of 75,000,000 acre-feet for any period of 10 consecutive years.”

The Lower Basin states of Arizona, California and Nevada contend that this provision is a “delivery obligation,” requiring the Upper Basin to ensure that over any 10-year period, a total of at least 75 million acre-feet flows to the Lower Basin.

By contrast, the Upper Basin states contend that the language merely creates a “non-depletion obligation” that caps their collective use at 7.5 million acre-feet per year in times when additional use by the Upper Basin would cause less than 75 million acre-feet to be delivered to the Lower Basin over a 10-year period.

This disagreement over the compact’s language is at the heart of the differences between the two basins.

A small source area

Nearly all of the water in the Colorado River system comes from snow that falls in the Rocky Mountains in the Upper Basin. About 85% of the Colorado Basin’s flows come from just 15% of the basin’s surface area. Most of the rest of the basin’s lands are arid or semi-arid, receiving less than 20 inches of precipitation a year and contributing little to the flows of the Colorado River and its tributaries.

Rain and snowfall vary dramatically from year to year, so over the course of the 20th century, the Colorado Basin states – with the assistance of the U.S. Bureau of Reclamation, the agency of the Department of the Interior responsible for operating federal water and power projects in the U.S. West – developed a complex system of reservoirs to capture the extra water in wet years so it could be available in drier years. The most notable reservoirs in the system are Lake Mead, impounded by Hoover Dam, which was completed in 1936, and Lake Powell, impounded by Glen Canyon Dam, completed in 1966.

Over the past 25 years, the quantity of water stored in Lake Mead and Lake Powell has declined significantly. A primary driver of this decline is a lengthy drought likely amplified by climate change: One study estimated that the region may be suffering its driest spell in 1,200 years.

But human errors are also adding up. The Colorado Compact’s original negotiators made unrealistically optimistic assumptions about the river’s average annual flow – perhaps knowingly. In their book “Science be Dammed,” Colorado River experts Eric Kuhn and John Fleck document how compact negotiators willfully or wishfully ignored available data about the river’s actual flows. Kuhn and Fleck argue the negotiators knew it would be decades before demand would exceed the river’s water supply, and they wanted to sell a big vision of Southwestern development that would merit massive federal financing for reservoirs and other infrastructure.

In addition, the current Colorado River system accounting does not factor in the roughly 1.3 million acre-feet of water lost annually from Lake Mead due to evaporation into the air or seepage into the ground. This accounting gap means that under normal annual releases to satisfy the apportionments to the Lower Basin and Mexico, Lake Mead’s water level is steadily declining.

Stabilization efforts

The seven Colorado River states and Mexico have taken significant steps to stabilize the reservoirs. In 2007, they agreed to new guidelines to coordinate the operations of Lake Mead and Lake Powell to prevent either reservoir from reaching catastrophically low levels. They also agreed to reduce the amount of water available to Arizona and Nevada depending on how low Lake Mead’s levels go.

When the 2007 guidelines proved insufficient to keep the reservoir levels from declining, the Colorado Basin states and Mexico agreed in 2019 to additional measures, authorizing releases from Upper Basin reservoirs under certain conditions and additional cuts to water users in the Lower Basin and Mexico.

By 2022, projections for the reservoir levels looked so dire that the states started negotiating additional near-term measures to reduce the amount of water users withdrew from the river. The federal government helped out, too: $4 billion of Inflation Reduction Act funding has helped pay the costs of water-conservation measures, primarily by agricultural districts, cities and tribes.

These reductions are real. In 2023, Arizona, California and Nevada used only 5.8 million acre-feet of Colorado River water – their lowest combined annual consumption since 1983. The Lower Basin’s total consumption in 2024 was slightly higher, at 6.09 million acre-feet.

A new opportunity?

With the 2007 guidelines and additional measures expiring in 2026, the deadline for a new agreement looms. As the Colorado River states try to work out a new agreement, Arizona’s new proposal of a supply-driven approach offers hope, but the devil’s in the details. Critical components of that approach have not been ironed out – for instance, the percentage of the river’s flows that would be available to Arizona, California and Nevada.

If the states can’t agree, there is a chance that the secretary of the Interior, acting through the Bureau of Reclamation, may decide on his own how to balance the reservoirs and how much water to deliver out of them. That decision would almost certainly be taken to court by states or water users unhappy with the result.

And the Lower Basin states have said they are fully prepared to go to court to enforce what they believe to be the Upper Basin’s delivery obligation, which, the Upper Basin has responded, it is prepared to dispute.

In the meantime, farmers in Arizona’s Yuma County and California’s Imperial County cannot be sure that in the next few years they will have enough water to produce winter vegetables and melons for the nation. The Colorado River Basin’s municipal water providers are worried about how they will meet demands for tap water for homes and businesses. And tribal nations fear that they will not have the water they need for their farms, communities and economies.

Sarah Porter is the Director of the Kyl Center for Water Policy, part of Arizona State University’s Morrison Institute for Public Policy. In 2021, the Kyl Center for Water Policy received a grant from the Walton Family Foundation to develop a data visualization tool showing how Colorado River shortage will impact cities, tribes and agricultural districts in Arizona.

– ref. As the Colorado River slowly dries up, states angle for influence over future water rights – https://theconversation.com/as-the-colorado-river-slowly-dries-up-states-angle-for-influence-over-future-water-rights-254132

Source: The Conversation – USA (2) – By Shannon Roberts, Associate Professor of Industrial Engineering, UMass Amherst

The last few weeks of summer, heading into Labor Day weekend, can sometimes mean vacations and driving more miles on the road for all people, including teens.

Traffic crashes are the No. 1 cause of death for teens, and the crash rate for teen drivers is disproportionately higher than the share of licensed teen drivers.

In addition to this grim statistic, summer is the riskiest time for teen drivers. The 100 deadliest days represent the period from Memorial Day to Labor Day when the number of fatal crashes involving teen drivers dramatically increases. A third of each year’s teen driver crashes occur during the summer.

We are scholars who research transportation safety and teen driver behavior. Our expertise helps us understand that these 100 days are not just a statistical fluke – they reflect a dangerous intersection of factors such as inexperience and a propensity to take risks.

What makes summer different?

Regardless of the season, some teen drivers engage in risky behaviors that increase their likelihood of a fatal crash, such as getting distracted, driving with friends in the vehicle, driving under the influence, not wearing seat belts and a lack of hazard awareness.

Teens also have more free time in the summer, since most aren’t in school. Combined with the longer days and better weather, teens drive more over the summer. More time on the road means more risk, especially for inexperienced drivers.

Teens may also be more likely to drive after dark during the summer, in comparison to more experienced drivers. But nighttime driving is also when visibility is reduced and crash risks are higher, particularly for teens who haven’t fully developed the skills necessary for night driving. This increased exposure, in addition to teens’ general risky driving tendencies, contributes to the 100 deadliest days for teen drivers.

The increased crash risk for teens over the summer isn’t equally distributed either. Crashes with teen drivers that lead to serious injuries are more likely to occur with male drivers, in rural areas, for those of lower socioeconomic status and for those with disorders, such as attention deficit and hyperactivity disorder.

Teaching young drivers

Driver’s education programs are the formal method to teach teen drivers the rules of the road.

In driver’s education programs, teens receive information about driver and road safety though classroom and behind-the-wheel instruction in preparation for the licensing exam. Some states require teens to complete a driver’s education course if they want to receive a license under the age of 18. Of teens who have a license, nearly 80% of them have gone through some form of driver’s education.

Though driver’s education programs can be helpful, their effects are not equally felt. In some states, teens and their guardians must pay out of pocket for driver’s education courses to obtain a license. This makes driver’s education and, as a consequence, obtaining a driver’s license inequitable.

There are also driving school deserts – areas where the poverty rate is 20% or above and there are no behind-the-wheel driver education courses within a 10- to 15-minute drive. This makes driver education courses inaccessible. Many of these driving school deserts happen to be in areas with high populations of minorities.

Over 20 years ago, graduated driver licensing was introduced to reduce teen crash rates. This is a phased licensing system wherein teen drivers are restricted in terms of when, where and with whom they can drive until they turn 18. Such a system allows teens to gradually learn and gain experience with driving over time.

Graduated driver licensing has been implemented in all 50 states, and it has been shown to reduce teen driver crash rates. However, its effectiveness is limited to those who participate in the system. A large number of teens are unlicensed and are of low socioeconomic status. Many of these unlicensed teens forgo the entire process and remain unlicensed but still drive, well into their 20s when the graduated driver licensing restrictions are lifted.

Making summer safer

There are two things people can do to turn the 100 deadliest days into the 100 safest days.

First, it is important that communities offer free supplementary training programs for teen drivers, because becoming a safe and responsible teen driver shouldn’t be limited to those with resources. As one example, in collaboration with industry partners, we have developed a program called Risk-ATTEND. It is a free, online, evidence-based program that teaches teen drivers how to anticipate risks while driving. Our research has shown that programs such as these can improve teen driving skills and may be especially effective for teen drivers in high-poverty areas.

Second, our research has shown that parents and guardians still play an important role in influencing teen driver behavior. Studies show that teens mirror the behaviors they observe: If they see adults text and drive, they’re more likely to do the same.

Once teenagers become old enough to drive, it is also important to establish rules and guidelines about expectations to establish clarity and accountability. Written agreements or checklists can address high-risk conditions such as nighttime driving, driving with other young passengers, phone use and adherence to speed limits.

Systems to help monitor and enforce rules have been shown to be effective in improving teen driver behavior. One such program is Checkpoints, which is a Connecticut-based program in which families agree to limit teen driving during high-risk conditions. Teens face consequences for violating these limits, such as a temporary loss of driving privileges. However, the limits are gradually lifted as they gain driving experience.

More than rules matter

Ultimately, preventing crashes in the summer and beyond extends beyond mere adherence to regulations. Avoiding them fundamentally hinges on cultivating a robust safety culture that emphasizes a collective commitment to risk reduction and continuous improvement in driving practices.

For teens, the summer months present unique challenges and opportunities.

Drawing on best practices, such as training programs, teens can build essential skills in varied conditions before gaining full, unsupervised privileges.

Shannon Roberts receives funding from the Massachusetts Department of Transportation, National Science Foundation, Sloan Foundation, and US Department of Transportation. She has received funding from GM and Toyota Collaborative Safety Research Center in past years.

Anuj Kumar Pradhan receives funding from the Massachusetts Department of Transportation, National Institutes of Health, and the US Department of Transportation. He has received funding from Toyota Collaborative Safety Research Center and State Farm in past years.

– ref. Teen drivers face unique challenges during ‘100 deadliest days’ of summer, but safety measures can make a difference – https://theconversation.com/teen-drivers-face-unique-challenges-during-100-deadliest-days-of-summer-but-safety-measures-can-make-a-difference-260899

Source: The Conversation – USA (2) – By A. Stefanie Ruiz, Assistant Professor in Nonprofit Leadership, College of Behavioral, Social and Health Sciences, Clemson University

“Born with voices that could drive back the darkness,” the character Celine, a former K-pop idol, narrates at the start of Netflix’s new release “KPop Demon Hunters.” “Our music ignites the soul and brings people together.”

The breakout success of “KPop Demon Hunters,” Netflix’s most-watched original animated film, highlights how “hallyu,” or the Korean Wave, keeps expanding its pop cultural reach. The movie, which follows a fictional K-pop girl group whose members moonlight as demon slayers, amassed over 26 million views globally in a single week and topped streaming charts in at least 33 countries.

From K-pop and K-dramas to beauty products and e-sports, hallyu – which refers to the global popularity of South Korean culture – has drawn in millions of fans worldwide. But beyond entertainment, many young people describe how their engagement with Korean culture supports their mental health and sense of belonging.

We conducted interviews with 30 non-Korean hallyu fans aged 18-30 in Philadelphia in 2019 to understand how they experience Korean cultural content. Our findings were recently published in the peer-reviewed World Leisure Journal.

The core themes, such as the emotional support, community building and cultural exploration offered by hallyu, remain relevant today, especially as Korean media continues to expand their global influence and resonate with new generations of fans.

A light space in a heavy world

Participants described hallyu, especially K-pop and K-dramas, as a refuge from the stress and negativity they associate with mainstream Western media.

“I think Western music is a lot … more mellow,” a 24-year-old social worker explained. “It’s like a blunt kind of depression … it doesn’t make you go out in the world and smile at everything.”

In contrast, K-pop was often described as uplifting, playful and emotionally resonant. This contrast was especially important for individuals who felt overwhelmed by the hypersexualized or violent content common in Western pop culture.

“I feel like the stories in [Korean dramas] make more of an effort to connect with people,” said a 22-year-old communications associate. “They’re not as explicit. [For instance, simply] holding hands is a huge deal.”

Another participant, a 19-year-old college student and part-time barista who identified as asexual, shared: “I really like seeing content where they portray a hug or simple kisses as extremely intimate. … [I]t just makes me more comfortable.”

Music as emotional medicine

For many interviewees, hallyu had become a form of emotional self-care.

“It supplements my happiness,” a 25-year-old researcher said. “I’m a pretty optimistic person; it just kind of supplements that baseline optimism.”

Others described how specific songs helped them through difficult times. The college student and barista recalled listening to the boy band BTS’ “Magic Shop” during a spell of depression. “I would just wrap a blanket around myself, sip tea … and it made me feel immensely better,” she said.

This therapeutic effect is not accidental. BTS, one of the most globally recognized K-pop groups, has built its brand around messages of self-love and mental health awareness.

“They try to spread a message of loving yourself,” a 24-year-old medical assistant explained. “Like no one can love you unless you love yourself first.”

Building community online and offline

Another key benefit of hallyu culture is the sense of community it fosters. Individuals from all backgrounds and ages connect through social media, fan clubs and local events.

“I’ve met a lot of people through [the K-pop club] on Temple’s campus,” one participant said. “We’d watch K-pop and K-dramas together. … [T]hat is still one of our major connections.”

Online platforms also play a crucial role. Individuals share translations, create fan art and organize charity projects in honor of their favorite idols.

“We do projects for BTS’ birthdays,” a 28-year-old government appraiser said. She also donated blood on the birthday of Mingyu, a member of the K-pop group Seventeen.

Exploring identity and culture

For many Asian American fans, hallyu has also become a way to explore and affirm their cultural identity.

“I think the Asian cultural dynamic … is familiar to me,” a Chinese American participant said. “It encouraged me to be more proud of my own culture.”

Another Chinese American participant, a third-year college student, reflected on how Korean dramas helped her appreciate traditional values: “They made me more aware … of how you should talk or act around people. It’s constantly reminding me of ways I can self-improve.”

Even non-Asian fans connected with the values portrayed in Korean media. One Jewish participant, a 26-year-old Ph.D. candidate, noted the similarities between Korean and Jewish family structures: “Our morals, our values … just fit very well together.”

A meaningful investment of time

While some fans acknowledged that their engagement with hallyu could be time-consuming, many saw it as a worthwhile investment.

“It’s probably an embarrassing amount of time,” one participant admitted. “But pretty much anytime I’m bored, I turn to K-pop.”

Another compared their hallyu consumption to “therapy sessions.”

Others described how, over time, they became more involved in fan communities or online content, and this deeper level of engagement often led to skill-building and personal growth as they learned video editing, translation, event planning and even fundraising. Participants who raised money for animal shelters or dance studios, for example, said they were inspired by the values promoted in hallyu culture. These efforts helped them feel more connected to both their idols and one another.

“I created a huge analysis on costuming in a certain music video for Seventeen,” a 26-year-old restaurant manager said. “I just couldn’t help myself.”

In a media landscape often dominated by cynicism and spectacle, the Korean Wave offers an alternative: a space where joy, vulnerability and connection are not only possible, but celebrated.

Read more of our stories about Philadelphia.

The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.

– ref. ‘KPop Demon Hunters’ is attracting huge audiences worldwide – young Philadelphians told us K-pop culture inspires innocence, joy and belonging – https://theconversation.com/kpop-demon-hunters-is-attracting-huge-audiences-worldwide-young-philadelphians-told-us-k-pop-culture-inspires-innocence-joy-and-belonging-262179

Source: The Conversation – USA (3) – By Christopher P. Holstege, Professor of Emergency Medicine and Pediatrics, University of Virginia

Enjoying the outdoors carries the danger of running into nature’s less-friendly side: toxic plants and animals.

As toxicologists at the University of Virginia’s Blue Ridge Poison Center, we see many patients each year suffering from itchy rashes from poison ivy and stings from wasps or bees.

Plants and animals deploy toxins most often in order to defend themselves. Learning how they do that and what happens when the human body is exposed to these substances can offer insights on how to prevent or manage these encounters with nature.

The goal is not to scare people away from the outdoors, but to equip them with the knowledge to appreciate these organisms’ intricate self-preservation strategies and to protect themselves in return.

Poison ivy, a ubiquitous source of itch

Whether in a remote state park or on a city playground, most people have encountered poison ivy. This plant is recognizable by its characteristic arrangement of leaves growing in groups of three with edges that vary from smooth to jagged. It can take many forms: a single small plant, a mass of ground cover, a small bush, or a climbing vine reaching many feet up a tree or building.

Poison ivy – its scientific name is Toxicodendron radicans – and its close relatives poison oak and poison sumac contain an oily substance called urushiol. This chemical is found in every part of the plant: the leaves, roots, stems and even the small white berries it produces in late summer.

About 75% of people will develop an allergic reaction on contact with urushiol. Urushiol has antimicrobial properties, and scientists think its job in the poison ivy plant is to protect it from diseases.

Because it is so oily, urushiol spreads easily. It can transfer from the plant to your skin, clothes, garden tools or even your pets. Direct plant contact isn’t the only risk: If urushiol is on your clothing or a pet’s fur and your skin later brushes against it, you can develop the same rash as you’d get from directly touching the plant.

From plant to skin

Urushiol triggers a delayed allergic reaction. When the oil touches your skin, it binds to skin cells, changing their shape. A molecule called CD1a then clocks urushiol as a foreign substance, prompting the immune system to mount an attack on the cells – hence the rash.

The symptoms do not appear instantly; the rash usually appears 12 to 48 hours after exposure. It often starts as redness and itching, then develops into small bumps or fluid-filled blisters. The reaction can be mild or severe, depending on how sensitive you are and how much urushiol got on your skin.

The rash itself isn’t contagious. Fluid from the blisters doesn’t spread it. What spreads the rash to other areas of your body or to others is the urushiol lingering on your skin, clothing, tools or pets. Once the oil is adequately washed away, the rash can’t spread to other people or to other areas of your body.

If you have touched poison ivy, wash the area as soon as you can with soap and water and change your clothes if possible. After that, the rash will eventually resolve on its own. You can help alleviate symptoms by using a topical steroid or anti-itch cream on the rash. In severe cases, or if the face is affected, patients may require oral steroids to treat the symptoms.

Bees and wasps: Home defenders

Bees and wasps are most active in the late summer. Because of this, we receive more frequent poison center calls about them during this season.

Bees and wasps generally sting to defend their hives or nests or to protect themselves from perceived threats. They store venom in their abdominal sacs. When they sting, the venom flows through their stinger and is injected into their target’s skin.

This venom is a clear, slightly acidic liquid loaded with various active ingredients. For example, it contains enzymes such as phospholipase A2 that break down cell membranes, and peptides such as melittin that cause pain. The venom also contains natural chemicals such as histamine and epinephrine that affect blood vessels and the immune system.

Sting mechanics

Unlike with poison ivy, where the immune system’s reaction to the substance causes irritation, with bee and wasp stings it’s primarily the substance itself that causes pain – although immune response can still play a role. As soon as the venom enters a person’s skin, their body reacts.

A sharp, burning pain comes first as the components of the venom begin to inflict damage, followed by redness and then swelling of the area. Symptoms commonly peak within a few hours and fade within a day. However, some people have stronger reactions with larger areas of swelling that can last for several days. This is because everyone’s immune system is slightly different, and some people tend to have stronger reactions than others to foreign substances.

In rare cases, the immune system overreacts, releasing large amounts of histamine and other chemicals all at once. Histamine is most often released in response to a foreign substance, causing symptoms of an allergic reaction. This can lead to anaphylaxis, a severe allergic reaction that can make breathing difficult, lower blood pressure and cause airway swelling, and which can quickly become life-threatening.

Getting stung multiple times at once can also be life-threatening due to the sheer amount of venom injected, even in people without a bee venom allergy.

If you’re stung and the stinger is stuck in the skin, it should be removed immediately by the quickest means available. Bee stingers are barbed and can continue to deliver venom for up to a minute. Most bee or wasp stings require only symptomatic treatment, such as an over-the-counter steroid cream or oral antihistamine to reduce itching and swelling.

However, people who begin to develop more severe symptoms such as full body hives, vomiting or difficulty breathing should immediately seek emergency care. Anaphylactic reactions require rapid treatment with a medication called epinephrine and close monitoring in the hospital.

The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.

– ref. A toxicologist’s guide to poison ivy’s itch and bee stings’ burning pain – 2 examples of nature’s chemical warfare – https://theconversation.com/a-toxicologists-guide-to-poison-ivys-itch-and-bee-stings-burning-pain-2-examples-of-natures-chemical-warfare-261156

Source: The Conversation – USA (3) – By Anand Kumar, Professor and Department Head of Psychiatry, University of Illinois Chicago

Over the past two centuries, vaccines have been critical for preventing infectious diseases. The World Health Organization estimates that vaccination prevents between 3 million and 5 million deaths annually from diseases like diphtheria, tetanus, influenza, measles and, more recently, COVID-19.

While there has long been broad scientific consensus that vaccines prevent or mitigate the spread of infections, there is new research suggesting that the therapeutic impact might go beyond the benefit of preventing infectious diseases.

An April 2025 study published in the prominent journal Nature found tantalizing evidence that the herpes zoster – or shingles – vaccine could lower the risk of dementia in the general population by as much as 20%.

We are a team of physician scientists with expertise in the clinical and basic science of neurodegenerative disorders and dementia.

We believe that this study potentially opens the door to other breakthroughs in understanding and treating dementia and other degenerative disorders of the brain.

A role for vaccines in reducing dementia risk?

One of the major challenges researchers face when trying to study the effects of vaccines is finding an unvaccinated “control group” for comparison – a group that is similar to the vaccine group in all respects, save for the fact that they haven’t received the active vaccine. That’s because it’s unethical to assign some patients to the control group and deprive them of vaccine protection against a disease such as shingles.

The Nature study took advantage of a policy change in Wales that went into effect in 2013, stating that people born on or after September 2, 1933, were eligible for the herpes zoster vaccination for at least a year, while those born before that cutoff date were not. The vaccine was administered to prevent shingles, a painful condition caused by the same virus that causes chickenpox, which can lie dormant in the body and be reactivated later in life.

The researchers used the policy change as a natural laboratory of sorts to study the effect of shingles vaccination on long-term health outcomes. In a statistically sophisticated analysis of health records, the team found that the vaccine reduced the probability of getting dementia by one-fifth over a seven-year period. This means that people who received the shingles vaccine were less likely to develop clinical dementia over the seven-year follow-up period, and women benefited more than men.

The study design allowed researchers to compare two groups without actively depriving any one group of access to vaccination. The two groups were also of comparable age and had similar medical comorbidities – meaning similar rates of other medical conditions such as diabetes or high blood pressure.

Results from this and other related studies raise the possibility that vaccines may have a broader role in experimental therapeutics outside the realm of infectious diseases.

These studies also raise provocative questions about how vaccines work and how our immune system can potentially prevent dementia.

How vaccines might be protective

One scientific explanation for the reduction of dementia by the herpes zoster vaccine could be the direct protection against the shingles virus, which may play a role in exacerbating dementia.

However, there is also the possibility that the vaccine may have conferred protection by activating the immune system and providing “trained immunity,” in which the immune system is strengthened by repeated exposure to vaccines or viruses.

The study did not differentiate between different types of dementia, such as dementia due to Alzheimer’s disease or dementia due to stroke. Additionally, researchers cannot draw any definitive conclusions about possible mechanisms for how the vaccines could be protective from an analysis of health records alone.

The next step would be a prospective, randomized, double-blind, placebo-controlled study – the “gold standard” for clinical trials in medicine – to directly examine how the herpes zoster vaccine compares with a placebo in their ability to reduce the risk of dementia over time. Such studies are necessary before any vaccines, as well as other potential therapies, can be recommended for routine clinical use in the prevention of dementia.

The challenges of untangling dementia

Dementia is a major noncommunicable disease that is a leading cause of death around the world.

A January 2025 study provided updated figures on lifetime dementia risk across different subsets of the U.S. population. The researchers estimate that the lifetime risk of dementia after age 55 is 42% – more than double earlier estimates. The dementia risk was 4% by age 75, and 20% by age 85, with the majority of risk occurring after 85. The researchers projected that the number of new cases of dementia in the U.S. would double over the next four decades from approximately 514,000 cases in 2020 to 1 million in 2060.

Once considered a disease largely confined to the developed world, the deleterious effects of dementia are now apparent throughout the globe, as life expectancy increases in many formerly developing countries. While there are different forms of dementia with varying clinical manifestations and underlying neurobiology, Alzheimer’s disease is the most common.

Prospective studies that specifically test how giving a vaccine changes the risk for future dementia may benefit from studying patient populations with specific types of dementia because each version of dementia might require distinct treatments.

Unfortunately, for the past two to three decades, the amyloid hypothesis of Alzheimer’s disease – which posits that accumulation of a protein called amyloid in the brain contributes to the disorder – dominated the scientific conversation. As a result, most of the efforts in the experimental therapeutics of Alzheimer’s disease have focused on drugs that lower the levels of amyloid in the brain.

However, results to date have been modest and disappointing. The two recently approved amyloid-lowering therapies have only a minimal impact on slowing the decline, are expensive and have potentially serious side effects. And no drug currently approved by the Food and Drug Administration for clinical use reverses the cognitive decline.

Studies based on health records suggest that past exposure to viruses increase the risk of dementia, while routine vaccines, including those against tetanus, diphtheria, pertussis, pneumonia, shingles and others, reduce the risk.

Innovation and an open mind

There is sometimes a tendency among scientists to cling to older, familiar models of disease and a reluctance to move in more unconventional directions.

Yet the process of doing science has a way of teaching researchers like us humility, opening our minds to new information, learning from our mistakes and going where that data takes us in our quest for effective, lifesaving therapies.

Vaccines may be one of those paths less traveled. It is an exciting possibility that may open the door to other breakthroughs in understanding and treating degenerative disorders of the brain.

Jalees Rehman receives funding from NIH.

Anand Kumar 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. Vaccines hold tantalizing promise in the fight against dementia – https://theconversation.com/vaccines-hold-tantalizing-promise-in-the-fight-against-dementia-257807

Source: The Conversation – USA (2) – By Gavin D. Madakumbura, Postdoctoral Researcher, University of California, Los Angeles

Fire season is expanding in California, with an earlier start to wildfire activity in most of the state. In parts of the northern mountains, the season is now starting more than 10 weeks earlier than it did in the 1990s, a new study shows.

Atmospheric scientists Gavin Madakumbura and Alex Hall, two authors of the study, explain how climate warming has been driving this trend and why the trend is likely to continue.

What did your study find about how wildfire season is changing?

Over the past three decades, California has seen a trend toward more destructive wildfire seasons, with more land burned, but also an earlier start to fire season. We wanted to find out how much of a role climate change was playing in that shift to an earlier start.

We looked at hundreds of thousands of fire records from 1992 to 2020 and documented when fire season started in each region of the state as temperatures rose and vegetation dried out.

While other research has observed changes in the timing of fire season in the western U.S., we identified the drivers of this trend and quantified their effects.

The typical onset of summer fire season, which is in May or June in many regions, has shifted earlier by at least one month in most of the state since the 1990s, and by about 2½ months in some regions, including the northern mountains. Of that, we found that human-caused climate change was responsible for advancing the season between six and 46 days earlier across most of the state from 1992 to 2020.

Our results suggest that as climate warming trends continue, this pattern will likely persist, with earlier starts to fire season in the coming years. This means longer fire seasons, increasing the potential for more of the state to burn.

California typically leads the nation in the number of wildfires, as well as the cost of wildfire damage. But the results also provide some insight into the risks ahead for other fire-prone parts of North America.

What’s driving the earlier start to fire season?

There are a few big contributors to long-term changes in wildfire activity. One is how much fuel is available to burn, such as grasses and trees. Another is the increase in ignition sources, including power lines, as more people move into wildland areas. A third is how dry the fuel is, or fuel aridity.

We found that fuel aridity, which is controlled by climate conditions, had the strongest influence on year-to-year shifts in the timing of the onset of fire season. The amount of potential fuel and increase in ignition sources, while contributing to fires overall, didn’t drive the trend in earlier fires.

Year-to-year, there will always be some natural fluctuations. Some years are wet, others dry. Some years are hotter than others. In our study, we separated the natural climate variations from changes driven by human-caused climate warming.

We found that increased temperatures and vapor pressure deficit – a measure of how dry the air is – are the primary ways climate warming is shifting the timing of the onset of fire season.

Just as a warmer, drier year can lead to an earlier fire season in a single year, gradual warming and drying caused by climate change are systematically advancing the start of fire seasons. This is happening because it is increasing fuel flammability.

Why has the start to fire season shifted more in some regions than others?

The biggest shifts we’ve seen in fire season timing in California have been in the northern mountains.

In the mountains, the winter snowpack typically keeps the ground and forests wet into summer, making it harder for fires to burn. But in warmer years, when the snowpack melts earlier, the fire potential rises earlier too.

Those warmer years are becoming more common. The reason climate change has a stronger impact in mountain regions is that snowpack is highly sensitive to warming. And when it melts sooner, vegetation dries out sooner.

In contrast, drier regions, such as desert ecoregions, are more sensitive to precipitation changes than to temperature changes. When assessing the influence of climate change in these areas, we mainly look at whether precipitation patterns have shifted due to climate warming. However, there is a lot of natural year-to-year variability in precipitation, and that makes it harder to identify the influence of climate change.

It’s possible that when precipitation changes driven by climate warming become strong enough, we may detect a stronger effect in these regions as well.

Gavin D. Madakumbura receives funding from the Gordon and Betty Moore Foundation.

Alex Hall receives funding from the NSF, DOE, NOAA, LADWP, and State of California, among other sources.

– ref. Wildfire season is starting weeks earlier in California – a new study shows how climate change is driving the expansion – https://theconversation.com/wildfire-season-is-starting-weeks-earlier-in-california-a-new-study-shows-how-climate-change-is-driving-the-expansion-262666