Category: English

Source: The Conversation – USA – By Randy Stein, Associate Professor of Marketing, California State Polytechnic University, Pomona

Why do some people endorse claims that can easily be disproved? It’s one thing to believe false information, but another to actively stick with something that’s obviously wrong.

Our new research, published in the Journal of Social Psychology, suggests that some people consider it a “win” to lean in to known falsehoods.

We are social psychologists who study political psychology and how people reason about reality. During the pandemic, we surveyed 5,535 people across eight countries to investigate why people believed COVID-19 misinformation, like false claims that 5G networks cause the virus.

The strongest predictor of whether someone believed in COVID-19-related misinformation and risks related to the vaccine was whether they viewed COVID-19 prevention efforts in terms of symbolic strength and weakness. In other words, this group focused on whether an action would make them appear to fend off or “give in” to untoward influence.

This factor outweighed how people felt about COVID-19 in general, their thinking style and even their political beliefs.

Our survey measured it on a scale of how much people agreed with sentences including “Following coronavirus prevention guidelines means you have backed down” and “Continuous coronavirus coverage in the media is a sign we are losing.” Our interpretation is that people who responded positively to these statements would feel they “win” by endorsing misinformation – doing so can show “the enemy” that it will not gain any ground over people’s views.

When meaning is symbolic, not factual

Rather than consider issues in light of actual facts, we suggest people with this mindset prioritize being independent from outside influence. It means you can justify espousing pretty much anything – the easier a statement is to disprove, the more of a power move it is to say it, as it symbolizes how far you’re willing to go.

When people think symbolically this way, the literal issue – here, fighting COVID-19 – is secondary to a psychological war over people’s minds. In the minds of those who think they’re engaged in them, psychological wars are waged over opinions and attitudes, and are won via control of belief and messaging. The U.S. government at various times has used the concept of psychological war to try to limit the influence of foreign powers, pushing people to think that literal battles are less important than psychological independence.

By that same token, vaccination, masking or other COVID-19 prevention efforts could be seen as a symbolic risk that could “weaken” one psychologically even if they provide literal physical benefits. If this seems like an extreme stance, it is – the majority of participants in our studies did not hold this mindset. But those who did were especially likely to also believe in misinformation.

In an additional study we ran that focused on attitudes around cryptocurrency, we measured whether people saw crypto investment in terms of signaling independence from traditional finance. These participants, who, like those in our COVID-19 study, prioritized a symbolic show of strength, were more likely to believe in other kinds of misinformation and conspiracies, too, such as that the government is concealing evidence of alien contact.

In all of our studies, this mindset was also strongly associated with authoritarian attitudes, including beliefs that some groups should dominate others and support for autocratic government. These links help explain why strongman leaders often use misinformation symbolically to impress and control a population.

Why people endorse misinformation

Our findings highlight the limits of countering misinformation directly, because for some people, literal truth is not the point.

For example, President Donald Trump incorrectly claimed in August 2025 that crime in Washington D.C. was at an all-time high, generating countless fact-checks of his premise and think pieces about his dissociation from reality.

But we believe that to someone with a symbolic mindset, debunkers merely demonstrate that they’re the ones reacting, and are therefore weak. The correct information is easily available, but is irrelevant to someone who prioritizes a symbolic show of strength. What matters is signaling one isn’t listening and won’t be swayed.

In fact, for symbolic thinkers, nearly any statement should be justifiable. The more outlandish or easily disproved something is, the more powerful one might seem when standing by it. Being an edgelord – a contrarian online provocateur – or outright lying can, in their own odd way, appear “authentic.”

Some people may also view their favorite dissembler’s claims as provocative trolling, but, given the link between this mindset and authoritarianism, they want those far-fetched claims acted on anyway. The deployment of National Guard troops to Washington, for example, can be the desired end goal, even if the offered justification is a transparent farce.

Is this really 5-D chess?

It is possible that symbolic, but not exactly true, beliefs have some downstream benefit, such as serving as negotiation tactics, loyalty tests, or a fake-it-till-you-make-it long game that somehow, eventually, becomes a reality. Political theorist Murray Edelman, known for his work on political symbolism, noted that politicians often prefer scoring symbolic points over delivering results – it’s easier. Leaders can offer symbolism when they have little tangible to provide.

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. Winning with misinformation: New research identifies link between endorsing easily disproven claims and prioritizing symbolic strength – https://theconversation.com/winning-with-misinformation-new-research-identifies-link-between-endorsing-easily-disproven-claims-and-prioritizing-symbolic-strength-265652

Source: The Conversation – USA (2) – By Andrew Muhammad, Professor of Agriculture and Resource Economics, University of Tennessee

Lumber, especially softwood lumber like pine and spruce, is critical to U.S. home construction. Its availability and price directly affect housing costs and broader economic activity in the building sector. The U.S. imports about 40% of the softwood lumber the nation uses each year, more than 80% of that from Canada.

President Donald Trump says that the U.S. has the capacity to meet 95% of softwood lumber demand and directed federal officials to update policies and regulatory guidelines to expand domestic timber harvesting and curb the arrival of foreign lumber.

On Sept. 29, 2025, he announced new tariffs on imported timber and wood products, including an additional 10% tariff on Canadian lumber. Those were added to 35% tariffs imposed on Canadian lumber in August. It was the latest phase in a long-standing dispute over the supply of lumber to builders in the U.S., which dates back to the 1980s, when U.S. producers began arguing that Canadian companies were benefiting from unfair subsidies from their government. Starting on Oct. 15, Canadian softwood lumber imports could face tariffs exceeding 45%.

As researchers studying the forestry sector and international trade, we recognize that the U.S. has ample forest resources. But replacing imports with domestic lumber isn’t as simple as it sounds.

There are differences in tree species and quality, and U.S. lumber often comes at a higher cost, even with tariffs on imports. Challenges like limited labor and manufacturing capacity require long-term investments, which temporary tariffs and uncertain trade policies often fail to encourage. In addition, the amount of lumber imported tends to mirror the boom-and-bust cycles of housing construction, a dynamic that tariffs alone are unlikely to change.

Trump’s moves

To boost U.S. logging, in March, Trump issued an executive order telling the departments of Interior and Agriculture to ease what he called “heavy-handed” regulations on timber harvesting. The executive order and a follow-up memo from Agriculture Secretary Brooke Rollins do not spell out specifics, but officials say more details are in the works that will simplify the timber harvesting process, with the goal of boosting domestic timber production by 25%.

That same month, Trump ordered the Commerce Department to assess how imports of timber, lumber and related wood products affect U.S. national security.

While that assessment was underway, in July, the Commerce Department published findings from a trade review of 2023 Canadian lumber imports. That inquiry alleged that Canadian companies were selling lumber to the U.S. at unfairly low prices, potentially leaving U.S. producers with lower sales or depressed prices. That finding was cited as the basis for the 35% August tariff announcement.

In its national security investigation initiated in March, the Commerce Department concluded that an overreliance on imported wood products means “the United States may be unable to meet demands for wood products that are crucial to the national defense and critical infrastructure.” The September tariff announcement is based on those findings.

Canadian lumber in the US market

In 1991, the U.S. imported 11.5 billion board feet (27 million cubic meters) of Canadian lumber. Those imports rose to a high of 22 billion board feet (52 million cubic meters) by 2005.

But as housing construction declined – especially during the Great Recession from 2007 to 2009 – imports dropped sharply, to less than 8.4 billion board feet (20 million cubic meters) in 2009. The current volume has not recovered to prerecession levels, rising only to 12 billion board feet (28 million cubic meters) in 2024.

The value of Canadian lumber has also fluctuated. Historically, prices for Canadian lumber have averaged about US$330 per thousand board feet ($140 per cubic meter). During and after the COVID-19 pandemic, import prices soared to almost $800 per thousand board feet ($340 per cubic meter). But since peaking in 2021 and 2022, prices have dropped significantly to $436 per thousand board feet ($185 per cubic meter) by 2024.

In total, in 2024, the U.S. imported more than $11 billion in forest and wood products from Canada. Softwood lumber accounted for almost half of that.

Lumber and housing

As personal income rises and populations grow, people seek to build new homes. As new home construction – called “housing starts” in economic data – increases, so does demand for softwood lumber to build those homes. And when housing starts slow, so does lumber demand.

For instance, housing starts fell during the Great Recession. They declined from a January 2006 peak of 2.3 million to less than 500,000 in January 2009 – a decrease of nearly 80%. In that same period, imports of Canadian lumber fell by more than 60%. Domestic softwood lumber production fell by more than 40%.

Both domestic and imported lumber prices can directly influence the overall cost of building homes, which in turn affects housing affordability. That said, lumber used for framing usually accounts for less than 10% of the total cost to build a new home. The effects of tariffs on new home construction may be significantly less than other factors, such as rising labor costs.

A matter of choice

The U.S. has a lot of potential lumber available. Especially in the South, the inventory of harvestable lumber has grown significantly over many years.

However, the types of wood available in the U.S. are not always the same as what’s available from Canadian imports. For framing, contractors may prefer spruce, northern pines and fir, naturally abundant in Canada, because they are lighter and less likely to warp than southern yellow pine, which is abundant in the southern U.S. Southern yellow pine is more commonly used to make utility poles and preservative-treated lumber for outdoor construction projects, such as decks.

Lumber from Idaho, eastern Oregon and eastern Washington, however, does share characteristics with Canadian species and could take the place of at least some Canadian lumber.

As the Trump administration seeks to boost domestic lumber, buyers will be looking not only at where their lumber came from, but what it costs and what type of lumber is best for what they need to accomplish.

Andrew Muhammad received funding from the U.S. Department of Agriculture to research timber demand in Vietnam.

Adam Taylor 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. Why higher tariffs on Canadian lumber may not be enough to stimulate long-term investments in US forestry – https://theconversation.com/why-higher-tariffs-on-canadian-lumber-may-not-be-enough-to-stimulate-long-term-investments-in-us-forestry-265713

Source: The Conversation – USA (2) – By Christine Keiner, Chair, Department of Science, Technology, and Society, Rochester Institute of Technology

If you visit the Erie Canal today, you’ll find a tranquil waterway and trail that pass through charming towns and forests, a place where hikers, cyclists, kayakers, bird-watchers and other visitors seek to enjoy nature and escape the pressures of modern life.

However, relaxation and scenic beauty had nothing to do with the origins of this waterway.

When the Erie Canal opened 200 years ago, on Oct. 26, 1825, the route was dotted with decaying trees left by construction that had cut through more than 360 miles of forests and fields, and life quickly sped up.

Mules on the towpath along the canal could pull a heavy barge at a clip of 4 miles per hour – far faster than the job of dragging wagons over primitive roads. Boats rushed goods and people between the Great Lakes heartland and the port of New York City in days rather than weeks. Freight costs fell by 90%.

As many books have proclaimed, the Erie Canal’s opening in 1825 solidified New York’s reputation as the Empire State. It also transformed the surrounding environment and forever changed the ecology of the Hudson River and the lower Great Lakes.

For environmental historians like me, the canal’s bicentennial provides an opportunity to reflect upon its complex legacies, including the evolution of U.S. efforts to balance economic progress and ecological costs.

Human and natural communities ruptured

The Haudenosaunee Confederacy, the Indigenous nations that the French called the Iroquois, engaged in canoe-based trade throughout the Great Lakes and Hudson River valley for centuries. In the 1700s, that began to change as American colonists took the land through brutal warfare, inequitable treaties and exploitative policies.

That Haudenosaunee dispossession made the Erie Canal possible.

After the Revolutionary War, commercial enthusiasm for a direct waterborne route to the West intensified. Canal supporters identified the break in the Appalachian Mountains at the junction of the Mohawk River and the Hudson as a propitious place to dig a channel to Lake Erie.

Yet cutting a 363-mile-long waterway through New York’s uneven terrain posed formidable challenges. Because the landscape rises 571 feet between Albany and Buffalo, a canal would require multiple locks to raise and lower boats.

Federal officials refused to finance such “internal improvements.” But New York politician DeWitt Clinton was determined to complete the project, even if it meant using only state funds. Critics mocked the $7 million megaproject, worth around US$170 million today, calling it “DeWitt’s Ditch” and “Clinton’s Folly.” In 1817, however, thousands of men began digging the 4-foot-deep channel using hand shovels and pickaxes.

The construction work produced engineering breakthroughs, such as hydraulic cement made from local materials and locks that lifted the canal’s water level about 60 feet at Lockport, yet it obliterated acres of wetlands and forests.

After riding a canal boat between Utica and Syracuse, the writer Nathaniel Hawthorne described the surroundings in 1835 as “now decayed and death-struck.”

However, most canalgoers viewed the waterway as a beacon of progress. As a trade artery, it made New York City the nation’s financial center. As a people mover, it fueled religious revivals, social reform movements and the growth of Great Lakes cities.

The Erie Canal’s socioeconomic benefits came with more environmental costs: The passageway enabled organisms from faraway places to reach lakes and rivers that had been isolated since the end of the last ice age.

An invasive species expressway

On Oct. 26, 1825, Gov. Clinton led a flotilla aboard the Seneca Chief from Buffalo to New York City that culminated in a grandiose ceremony.

To symbolize the global connections made possible by the new canal, participants poured water from Lake Erie and rivers around the world into the Atlantic at Sandy Hook, a sand spit off New Jersey at the entrance to New York Harbor. Observers at the time described the ritual of “commingling the waters of the Lakes with the Ocean” in matrimonial terms.

Clinton was an accomplished naturalist who had researched the canal route’s geology, birds and fish. He even predicted that the waterway would “bring the western fishes into the eastern waters.”

Biologists today would consider the “Wedding of the Waters” event a biosecurity risk.

The Erie Canal and its adjacent feeder rivers and reservoirs likely enabled two voracious nonnative species, the Atlantic sea lamprey and alewife, to enter the Great Lakes ecosystem. By preying on lake trout and other highly valued native fish, these invaders devastated the lakes’ commercial fisheries. The harvest dropped by a stunning 98% from the previous average by the early 1960s.

Tracing their origins is tricky, but historical, ecological and genetic data suggest that sea lampreys and alewives entered Lake Ontario via the Erie Canal during the 1860s. Later improvements to the Welland Canal in Canada enabled them to reach the upper Great Lakes by the 1930s.

Protecting the $5 billion Great Lakes fishery from these invasive organisms requires constant work and consistent funding. In particular, applying pesticides and other techniques to control lamprey populations costs around $20 million per year.

The invasive species that has inflicted the most environmental and economic harm on the Great Lakes is the zebra mussel. Zebra mussels traveled from Eurasia via the ballast water of transoceanic ships using the St. Lawrence Seaway during the 1980s. The Erie Canal then became a “mussel expressway” to the Hudson River.

The hungry invading mussels caused a nearly tenfold reduction of phytoplankton, the primary food of many species of the Hudson River ecosystem. This competition for food, along with pollution and habitat degradation, led to the disappearance of two common species of the Hudson’s native pearly mussels.

Today, the Erie Canal remains vulnerable to invasive plants, such as water chestnut and hydrilla, and invasive animals such as round goby. Boaters, kayakers and anglers can help reduce bioinvasions by cleaning, draining and drying their equipment after each use to avoid carrying invasive species to new locations.

A recreational treasure

During the Gilded Age in the late 1800s, the Erie Canal sparked a utilitarian sense of environmental concern. Timber cutting in the Adirondack Mountains was causing so much erosion that the eastern canal’s feeder rivers were filling up with silt.

To protect these waterways, New York created Adirondack Park in 1892. Covering 6 million acres, the park balances forest preservation, recreation and commercial use on a unique mix of public and private lands.

Erie Canal shipping declined during the 20th century with the opening of the deeper and wider St. Lawrence Seaway and competition from rail and highways. The canal still supports commerce, but the Erie Canalway National Heritage Corridor now provides an additional economic engine.

In 2024, 3.84 million people used the Erie Canalway Trail for cycling, hiking, kayaking, sightseeing and other adventures. The tourists and day-trippers who enjoy the historic landscape generate over $300 million annually.

Over the past 200 years, the Erie Canal has both shaped, and been shaped by, ecological forces and changing socioeconomic priorities. As New York reimagines the canal for its third century, the artificial river’s environmental history provides important insights for designing technological systems that respect human communities and work with nature rather than against it.

Christine Keiner 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. Erie Canal’s 200th anniversary: How a technological marvel for trade changed the environment forever – https://theconversation.com/erie-canals-200th-anniversary-how-a-technological-marvel-for-trade-changed-the-environment-forever-263320

Source: The Conversation – USA (3) – By Carol Mathews, Professor of Psychiatry, University of Florida

Many news outlets have reported an increase – or surge – in attention-deficit/hyperactivity disorder, or ADHD, diagnoses in both children and adults. At the same time, health care providers, teachers and school systems have reported an uptick in requests for ADHD assessments.

These reports have led some experts and parents to wonder whether ADHD is being overdiagnosed and overtreated.

As researchers who have spent our careers studying neurodevelopmental disorders like ADHD, we are concerned that fears about widespread overdiagnosis are misplaced, perhaps based on a fundamental misunderstanding of the condition.

Understanding ADHD as one end of a spectrum

Discussions about overdiagnosis of ADHD imply that you either have it or you don’t.

However, when epidemiologists ask people in the general population about their symptoms of ADHD, some have a few symptoms, some have a moderate level, and a few have lots of symptoms. But there is no clear dividing line between those who are diagnosed with ADHD and those who are not, since ADHD – much like blood pressure – occurs on a spectrum.

Treating mild ADHD is similar to treating mild high blood pressure – it depends on the situation. Care can be helpful when a doctor considers the details of a person’s daily life and how much the symptoms are affecting them.

Not only can ADHD symptoms be very different from person to person, but research shows that ADHD symptoms can change within an individual. For example, symptoms become more severe when the challenges of life increase.

ADHD symptoms fluctuate depending on many factors, including whether the person is at school or home, whether they have had enough sleep, if they are under a great deal of stress or if they are taking medications or other substances. Someone who has mild ADHD may not experience many symptoms while they are on vacation and well rested, for example, but they may have impairing symptoms if they have a demanding job or school schedule and have not gotten enough sleep. These people may need treatment for ADHD in certain situations but may do just fine without treatment in other situations.

This is similar to what is seen in conditions like high blood pressure, which can change from day to day or from month to month, depending on a person’s diet, stress level and many other factors.

Can ADHD symptoms change over time?

ADHD symptoms start in early childhood and typically are at their worst in mid-to late childhood. Thus, the average age of diagnosis is between 9 and 12 years old. This age is also the time when children are transitioning from elementary school to middle school and may also be experiencing changes in their environment that make their symptoms worse.

Classes can be more challenging beginning around fifth grade than in earlier grades. In addition, the transition to middle school typically means that children move from having all their subjects taught by one teacher in a single classroom to having to change classrooms with a different teacher for each class. These changes can exacerbate symptoms that were previously well-controlled.

Symptoms can also wax and wane throughout life. For most people, symptoms improve – but may not completely disappear – after age 25, which is also the time when the brain has typically finished developing.

Psychiatric problems that often co-occur with ADHD, such as anxiety or depression, can worsen ADHD symptoms that are already present. These conditions can also mimic ADHD symptoms, making it difficult to know which to treat. High levels of stress leading to poorer sleep, and increased demands at work or school, can also exacerbate or cause ADHD-like symptoms.

Finally, the use of some substances, such as marijuana or sedatives, can worsen, or even cause, ADHD symptoms. In addition to making symptoms worse in someone who already has an ADHD diagnosis, these factors can also push someone who has mild symptoms into full-blown ADHD, at least for a short time.

The reverse is also true: Symptoms of ADHD can be minimized or reversed in people who do not meet full diagnostic criteria once the external cause is removed.

How prevalence is determined

Clinicians diagnose ADHD based on symptoms of inattention, hyperactivity and impulsivity. To make an ADHD diagnosis in children, six or more symptoms in at least one of these three categories must be present. For adults, five or more symptoms are required, but they must begin in childhood. For all ages, the symptoms must cause serious problems in at least two areas of life, such as home, school or work.

Current estimates show that the strict prevalence of ADHD is about 5% in children. In young adults, the figure drops to 3%, and it is less than 1% after age 60. Researchers use the term “strict prevalence” to mean the percentage of people who meet all of the criteria for ADHD based on epidemiological studies. It is an important number because it provides clinicians and scientists with an estimate on how many people are expected to have ADHD in a given group of people.

In contrast, the “diagnosed prevalence” is the percentage of people who have been diagnosed with ADHD based on real-world assessments by health care professionals. The diagnosed prevalence in the U.S. and Canada ranges from 7.5% to 11.1% in children under age 18. These rates are quite a bit higher than the strict prevalence of 5%.

Some researchers claim that the difference between the diagnosed prevalence and the strict prevalence means that ADHD is overdiagnosed.

We disagree. In clinical practice, the diagnostic rules allow a patient to be diagnosed with ADHD if they have most of the symptoms that cause distress, impairment or both, even when they don’t meet the full criteria. And much evidence shows that increases in the diagnostic prevalence can be attributed to diagnosing milder cases that may have been missed previously. The validity of these mild diagnoses is well-documented.

Consider children who have five inattentive symptoms and five hyperactive-impulsive symptoms. These children would not meet strict diagnostic criteria for ADHD even though they clearly have a lot of ADHD symptoms. But in clinical practice, these children would be diagnosed with ADHD if they had marked distress, disability or both because of their symptoms – in other words, if the symptoms were interfering substantially with their everyday lives.

So it makes sense that the diagnosed prevalence of ADHD is substantially higher than the strict prevalence.

Implications for patients, parents and clinicians

People who are concerned about overdiagnosis commonly worry that people are taking medications they don’t need or that they are diverting resources away from those who need it more. Other concerns are that people may experience side effects from the medications, or that they may be stigmatized by a diagnosis.

Those concerns are important. However, there is strong evidence that underdiagnosis and undertreatment of ADHD lead to serious negative outcomes in school, work, mental health and quality of life.

In other words, the risks of not treating ADHD are well-established. In contrast, the potential harms of overdiagnosis remain largely unproven.

It is important to consider how to manage the growing number of milder cases, however. Research suggests that children and adults with less severe ADHD symptoms may benefit less from medication than those with more severe symptoms.

This raises an important question: How much benefit is enough to justify treatment? These are decisions best made in conversations between clinicians, patients and caregivers.

Because ADHD symptoms can shift with age, stress, environment and other life circumstances, treatment needs to be flexible. For some, simple adjustments like classroom seating changes, better sleep or reduced stress may be enough. For others, medication, behavior therapy or a combination of these interventions may be necessary. The key is a personalized approach that adapts as patients’ needs evolve over time.

Carol Mathews receives funding from the National Institutes of Health and the International OCD Foundation. She is affiliated with the International OCD Foundation, and the Family Foundation for OCD Research. She acts as a consultant for the Office of Mental Health for the State of New York.

Stephen V. Faraone receives research funding from the National Institutes of Health, the European Union, the Upstate Foundation and Supernus Pharmaceuticals. With his institution, he holds US patent US20130217707 A1 for the use of sodium-hydrogen exchange inhibitors in the treatment of ADHD. His continuing medical education programs are supported by The Upstate Foundation, Corium Pharmaceuticals, Tris Pharmaceuticals and Supernus Pharmaceuticals. He acts as a consultant to multiple pharmaceutical companies.

– ref. Yes, ADHD diagnoses are rising, but that doesn’t mean it’s overdiagnosed – https://theconversation.com/yes-adhd-diagnoses-are-rising-but-that-doesnt-mean-its-overdiagnosed-257108

Source: The Conversation – USA (3) – By Richard J. Price, Professor of Biomedical Engineering, University of Virginia

Sound waves at frequencies above the threshold for human hearing are routinely used in medical care. Also known as ultrasound, these sound waves can help clinicians diagnose and monitor disease, and can also provide first glimpses of your newest family members.

And now, patients with conditions ranging from cancer to neurodegenerative diseases like Alzheimer’s may soon benefit from recent advances in this technology.

I am a biomedical engineer who studies how focused ultrasound – the concentration of sound energy into a specific volume – can be fine-tuned to treat various conditions. Over the past few years, this technology has seen significant growth and use in the clinic. And researchers continue to discover new ways to use focused ultrasound to treat disease.

A brief history of focused ultrasound

Ultrasound is generated with a probe containing a material that converts electrical current into vibrations, and vice versa. As ultrasound waves pass through the body, they reflect off the boundaries of different types of tissue. The probe detects these reflections and converts them back into electrical signals that computers can use to create images of those tissues.

Over 80 years ago, scientists found that focusing these ultrasonic waves into a volume about the size of a grain of rice can heat up and destroy brain tissue. This effect is analogous to concentrating sunlight with a magnifying glass to ignite a dry leaf. Early investigators began testing how focused ultrasound could treat neurological disorders, pain and even cancer.

Yet, despite these early findings, technical hurdles stood in the way of applying focused ultrasound in the clinic. For example, because the skull absorbs ultrasound energy, sending focusing beams with high enough energy to reach damaged brain tissue proved difficult. Researchers eventually overcame this problem by integrating large arrays of ultrasound transducers – the probes that convert between electrical signals and vibrations – with image-based information about skull shape and density. This change allowed researchers to better fine-tune the beams to their targets.

It is only after scientists made key advances in imaging technology and acoustic physics in recent years that the promise of ultrasound is being realized in the clinic. Hundreds of clinical trials aimed at treating dozens of conditions have been completed or are ongoing. Researchers have found notable success on a condition called essential tremor, which leads to uncontrolled shaking, usually of the hands. Focused ultrasound treatments for essential tremor are now performed routinely at many locations around the world.

I believe some of the most exciting applications for focused ultrasound include improving drug delivery to the brain, stimulating immune responses against cancer, and treating rare diseases of the central nervous system.

Delivering drugs to the brain

The blood-brain barrier is evolution’s exquisite solution to keeping noxious substances away from this most critical organ. The blood-brain barrier is comprised of very tightly connected cells lining the inside of blood vessels. It only allows certain types of molecules to enter the brain, protecting against pathogens and toxins. However, the blood-brain barrier is problematic when it comes to treating disease because it blocks therapies from reaching their intended target.

More than 20 years ago, pioneering studies determined that sending low-intensity pulses of focused ultrasound could temporarily open the blood-brain barrier by causing microbubbles in blood vessels to oscillate. This oscillation pushes and pulls on the surrounding vessel walls, briefly opening tiny pores that allow drugs in the bloodstream to penetrate into the brain. Critically, the blood-brain barrier opens only where the focused ultrasound is applied.

After many years of testing the safety of this technique and improving control of ultrasound energy, researchers have developed several devices using focused ultrasound to open the blood-brain barrier for treatment. Clinical trials testing the ability of these devices to deliver drugs to the brain to treat conditions like glioblastoma, brain metastases and Alzheimer’s disease are underway.

In parallel, there has been significant progress in developing gene therapies for numerous brain diseases. Gene therapy involves fixing or replacing faulty genetic material to treat a specific disease. Applying gene therapy to the brain is especially challenging because such therapies typically do not cross the blood-brain barrier.

Animal studies have shown that using focused ultrasound to open the blood-brain barrier can facilitate the delivery of gene therapies to their intended targets in the brain, opening doors to testing this technique in people.

Stimulating immune responses against cancer

Cancer immunotherapy instructs the patient’s own immune system to fight the disease. However, many patients – especially those afflicted with breast cancer, pancreatic cancer and glioblastoma – have tumors that are immunologically “cold,” meaning they are unresponsive to traditional immunotherapies.

Researchers have learned that focused ultrasound can destroy solid tumors in ways that allow the immune system to better recognize and destroy cancer cells. One way focused ultrasound does this is by turning tumors into debris that then literally flows to the lymph nodes. Once immune cells in the lymph nodes encounter this debris, they can initiate an immune response specifically against the cancer.

Inspired by these breakthroughs, the University of Virginia started the world’s first focused ultrasound immuno-oncology center in 2022 to support research in this area and push the most promising approaches to the clinic. For example, my colleagues are running a clinical trial at the center to test the use of focused ultrasound and immunotherapy to treat patients with advanced melanoma.

Treating rare diseases with focused ultrasound

Research on focused ultrasound has primarily focused on the most devastating and prevalent diseases, such as cancer and Alzheimer’s disease. However, I believe that further developments in, and increased use of, focused ultrasound in the clinic will eventually benefit patients with rare diseases.

One rare disease of particular interest for my lab is cerebral cavernous malformation, or CCM. CCMs are lesions in the brain that occur when the cells that make up blood vessels undergo uncontrolled growth. While uncommon, when these lesions grow and hemorrhage, they can cause debilitating neurological symptoms. The most common treatment for CCM is surgical removal of the brain lesions; however, some CCMs are located in brain areas that are difficult to access, creating a risk of side effects. Radiation is another treatment option, but it, too, can lead to serious adverse effects.

We found that using focused ultrasound to open the blood-brain barrier can improve drug delivery to CCMs. Additionally, we also observed that focused ultrasound treatment itself could stop CCMs from growing in mice, even without administering a drug. While we don’t yet understand how focused ultrasound is stabilizing CCMs, abundant research on the safety of using this technique in patients treated for other conditions has allowed neurosurgeons to begin designing clinical trials testing the use of this technique on people with CCM.

With further research and advancements, I am hopeful that focused ultrasound can become a viable treatment option for many devastating rare diseases.

Richard J. Price receives funding from the National Institutes of Health and the UVA Focused Ultrasound Cancer Immunotherapy Center.

– ref. Focused sound energy holds promise for treating cancer, Alzheimer’s and other diseases – https://theconversation.com/focused-sound-energy-holds-promise-for-treating-cancer-alzheimers-and-other-diseases-262622