Sharp rise in memory and thinking problems among U.S. adults, study finds

WHY THEY VOTED FOR TRUMP

American Academy of Neurology

Highlights:

• Overall rates of self-reported cognitive disability rose from 5.3% to 7.4% in the last decade.
• Rates nearly doubled among younger adults ages 18 to 39.
• People with annual incomes under $35,000 and less education saw the biggest increases.
• American Indian and Alaska Native adults had the highest reported rates.
• Study authors call for more research into social and economic drivers.

MINNEAPOLIS – A growing number of U.S. adults—particularly those under 40—are reporting serious challenges with memory, concentration and decision-making, according to a new study published in the September 24, 2025, online issue of Neurology®, the medical journal of the American Academy of Neurology.

“Challenges with memory and thinking have emerged as a leading health issue reported by U.S. adults,” said study author Adam de Havenon, MD, MS, of Yale School of Medicine in New Haven, Connecticut, and a Fellow of the American Academy of Neurology. “Our study shows that these difficulties may be becoming more widespread, especially among younger adults, and that social and structural factors likely play a key role.”

Researchers analyzed data from over 4.5 million survey responses from adults collected annually between 2013 and 2023. Participants were asked, “Because of a physical, mental, or emotional condition, do you have serious difficulty concentrating, remembering, or making decisions?” Those who answered “yes” were classified as having a cognitive disability. Researchers excluded responses from people who reported depression, along with data from the year 2020 due to the unique impacts of the COVID-19 pandemic.

The rate of cognitive disability in the U.S. rose from 5.3% in 2013 to 7.4% in 2023, with the first increase appearing in 2016. The largest increase was among adults ages under 40. For this group, the rate nearly doubled — climbing from 5.1% to 9.7%. In contrast, rates among those age 70 and older declined slightly, from 7.3% in 2013 to 6.6% over the same period.

While the survey is not a measure of cognitive impairment, de Havenon noted the growing prevalence of self-reported cognitive disability in younger adults reflects important public health trends.

Researchers found adults with household incomes below $35,000 consistently reported the highest rates—rising from 8.8% to 12.6% over the study period. By contrast, those with incomes over $75,000 had substantially lower rates, increasing only from 1.8% to 3.9%. For education, rates among adults without a high school diploma rose from 11.1% to 14.3% while rates among college graduates rose from 2.1% to 3.6% over the study period.

While most of the respondents were white, rates rose across nearly all racial and ethnic groups:

• American Indian and Alaska Native adults: highest prevalence, from 7.5% to 11.2%
• Hispanic adults: from 6.8% to 9.9%
• Black adults: from 7.3% to 8.2%
• White adults: from 4.5% to 6.3%
• Asian adults: from 3.9% to 4.8%

“These findings suggest we’re seeing the steepest increases in memory and thinking problems among people who already face structural disadvantages,” de Havenon said. “We need to better understand and address the underlying social and economic factors that may be driving this trend.”

“More research is also needed to understand what’s driving the large increase in rates among younger adults, given the potential long-term implications for health, workforce productivity and health care systems,” de Havenon continued. “It could reflect actual changes in brain health, better awareness and willingness to report problems, or other health and social factors. But regardless of possible causes, the rise is real—and it’s especially pronounced in people under 40.”

A limitation of the study was that data was gathered through telephone surveys and people providing responses may not have recalled all information accurately. Another limitation was the broad definition of disability.

Discover more about brain health at BrainandLife.org, from the American Academy of Neurology. This resource also offers a magazine, podcast, and books that connect patients, caregivers and anyone interested in brain health with the most trusted information, straight from the world’s leading experts in brain health. Follow Brain & Life® on Facebook, X, and Instagram.

The American Academy of Neurology is the leading voice in brain health. As the world’s largest association of neurologists and neuroscience professionals with more than 40,000 members, the AAN provides access to the latest news, science and research affecting neurology for patients, caregivers, physicians and professionals alike. The AAN’s mission is to enhance member career fulfillment and promote brain health for all. A neurologist is a doctor who specializes in the diagnosis, care and treatment of brain, spinal cord and nervous system diseases such as Alzheimer's disease, stroke, concussion, epilepsy, Parkinson's disease, multiple sclerosis, headache and migraine.

Explore the latest in neurological disease and brain health, from the minds at the AAN at AAN.com or find us on Facebook, X, Instagram, LinkedIn, and YouTube.

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Journal

Neurology

 

Caring for a baby makes the world seem more dangerous

Cornell University

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ITHACA, N.Y. — In a potentially threatening situation, the world looks more dangerous when caring for a baby, finds first-of-its-kind Cornell University psychology research using virtual environments to explore parenting dynamics.

When playing an online game that placed an adult on the side of a road after running out of gas, both parents and nonparents were quicker to detect oncoming traffic—and rated cars as moving faster—when they had to keep a virtual baby out of harm’s way. Reactions were quicker when looking after a crawling infant than a dog or a toy robot.

The findings suggest that infants’ appearance and movements lead adults to interpret sensory information differently, which supports babies’ safety and learning. This automatic behavior likely evolved because humans are a slowly developing (altricial) species, with infants who begin to move and explore long before they have the cognitive capacities to stay safe while doing so.

“It’s not a question of multitasking that caused these adults to perceive the cars as moving faster or to see them as more dangerous – it was having the baby there,” said Michael Goldstein, professor of psychology and co-author of “The Dynamics of Perception in Caregiving: How Infants Change the Way We See the World,” published in Child Development.

In a pair of experiments, the online game-players scored points for flagging down cars that appeared at random intervals, traveling between 30 and 70 mph. The first study, including 65 parents and 31 nonparents, introduced a stationary, crawling or walking baby that players could pick up if it moved too close to the road. In the second study (16 parents, 21 nonparents), players might be responsible for a crawling baby, a mutt or a mobile robot.

Goldstein, director of the Behavioral Analysis of Beginning Years (B.A.B.Y.) Laboratory, was initially surprised by how similarly parents and nonparents behaved. But upon reflection, he said it made sense that anyone in an alloparental species—a species in which individuals other than biological parents help care for young—would react quickly to protect another’s child.

The researchers also observed women reacting faster than men, suggesting a possible gender difference. Goldstein said that effect merits further investigation, but could also be due to the study sample including more women who were primary caregivers.

“Evolution has shaped adults to have an automatic and deep understanding of what it takes to keep a baby safe and provide information for that baby,” Goldstein said.

For additional information, see this Cornell Chronicle story.

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Journal

Child Development

DOI

10.1111/cdev.70026 

Article Title

The Dynamics of Perception in Caregiving: How Infants Change the Way We See the World

 

Raising money for a charity? Don't bark up the wrong tree.

Dartmouth study finds people without pets are more philanthropic than cat or dog owners.

Dartmouth College

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Dog owners are often associated with personality traits of being social and community-oriented while "cat people" are often thought of as introverted and more open-minded, according to prior research.

But if you're about to raise money for a charity from people with pets, you may want to think about the strategy.

A new Dartmouth study finds that cat owners donate slightly more than dog owners, and also donate more often and more diversely. However, people without pets donate the most.

The findings are published in the journal Anthrozoӧs.

To examine philanthropic behavior by pet ownership, including how personality traits may come into play, the study looked at approximately 63 million donors and 788 million transactions, totaling nearly $70 billion over a 10-year period between 2013 and 2022. The data was obtained from the cloud-computing management company Snowflake.

The study assessed donation amounts between $20 and $100,000 and their frequency, along with the age, gender, race, marital status, number of children, income, education, and partisanship of the donors. 

To capture the intricate relationships between the categorical features, a machine learning model called CatBoost, which stands for categorical boosting, was used.
 

Pet Owner Type	Total Donations by Pet Owner (2013-2022)	Donation Frequency (2013-2022)
No pets	$1,060	11
Cat owners	$780	15
Dog owners	$700	13
Both cat and dog owners	$630	14

Prior research in psychology has shown that openness is often correlated with higher levels of giving. If some cat owners are in fact more open and more neurotic than dog owners, these personality traits may have been a contributing factor to explain the recent study's results, including why cat people gave more and did so more often.

"My research shows how pet ownership reflects complex personality differences, even when it comes to philanthropy," says study author Herbert Chang ’18, an assistant professor of quantitative social science at Dartmouth. "They're not huge divergences, but they are meaningful and reflect everyday intuitions toward dog and cat owners."

Chang says that the differences in donation behavior in both amount and frequency could be useful for marketers as they work to identify and reach target audiences for charitable campaigns.

Chang is available for comment at: herbert.chang@dartmouth.edu.

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Journal

Anthrozoös

DOI

10.1080/08927936.2025.2544418 

Method of Research

Data/statistical analysis

Article Title

Pet Ownership Ties As Indicators for Giving Behavior

Article Publication Date

19-Sep-2025

An eco-friendly way to see in the dark

NYU Tandon develops environmentally compliant alternative to toxic heavy metals in infrared imaging

NYU Tandon School of Engineering

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Manufacturers of infrared cameras face a growing problem: the toxic heavy metals in today's infrared detectors are increasingly banned under environmental regulations, forcing companies to choose between performance and compliance.

This regulatory pressure is slowing the broader adoption of infrared detectors across civilian applications, just as demand in fields like autonomous vehicles, medical imaging and national security is accelerating.

In a paper published in ACS Applied Materials & Interfaces, researchers at NYU Tandon School of Engineering reveal a potential solution that uses environmentally friendly quantum dots to detect infrared light without relying on mercury, lead, or other restricted materials.

The researchers use colloidal quantum dots which upends the age-old, expensive, and tedious processing of infrared detectors. Traditional devices are fabricated through slow, ultra-precise methods that place atoms almost one by one across the pixels of a detector — much like assembling a puzzle piece by piece under a microscope.

Colloidal quantum dots are instead synthesized entirely in solution, more like brewing ink, and can be deposited using scalable coating techniques similar to those used in roll-to-roll manufacturing for packaging or newspapers. This shift from painstaking assembly to solution-based processing dramatically reduces manufacturing costs and opens the door to widespread commercial applications.

"The industry is facing a perfect storm where environmental regulations are tightening just as demand for infrared imaging is exploding," said Ayaskanta Sahu, associate professor in the Department of Chemical and Biomolecular Engineering (CBE) at NYU Tandon and the study's senior author. "This creates real bottlenecks for companies trying to scale up production of thermal imaging systems."

Another challenge the researchers addressed was making the quantum dot ink conductive enough to relay signals from incoming light. They achieved this using a technique called solution-phase ligand exchange, which tailors the quantum dot surface chemistry to enhance performance in electronic devices. Unlike traditional fabrication methods that often leave cracked or uneven films, this solution-based process yields smooth, uniform coatings in a single step — ideal for scalable manufacturing.

The resulting devices show remarkable performance: they respond to infrared light on the microsecond timescale — for comparison, the human eye blinks at speeds hundreds of times slower — and they can detect signals as faint as a nanowatt of light.

"What excites me is that we can take a material long considered too difficult for real devices and engineer it to be more competitive," said graduate researcher Shlok J. Paul, lead author on the study. "With more time this material has the potential to shine deeper in the infrared spectrum where few materials exist for such tasks."

This work adds to earlier research from the same lead researchers that developed new transparent electrodes using silver nanowires. Those electrodes remain highly transparent to infrared light while efficiently collecting electrical signals, addressing one component of the infrared camera system.

Combined with their earlier transparent electrode work, these developments address both major components of infrared imaging systems. The quantum dots provide environmentally compliant sensing capability, while the transparent electrodes handle signal collection and processing.

This combination addresses challenges in large-area infrared imaging arrays, which require high-performance detection across wide areas and signal readout from millions of individual detector pixels. The transparent electrodes allow light to reach the quantum dot detectors while providing electrical pathways for signal extraction.

"Every infrared camera in a Tesla or smartphone needs detectors that meet environmental standards while remaining cost-effective," Sahu said. "Our approach could help make these technologies much more accessible."

The performance still falls short of the best heavy-metal-based detectors in some measurements. However, the researchers expect continued advances in quantum dot synthesis and device engineering could reduce this gap.

In addition to Sahu and Paul, the paper's authors are Letian Li, Zheng Li, Thomas Kywe, and Ana Vataj, all from NYU Tandon CBE. The work was supported by the Office of Naval Research and the Defense Advanced Research Projects Agency.

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Journal

ACS Applied Materials & Interfaces

DOI

10.1021/acsami.5c12011 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Heavy Metal Free Ag2Se Quantum Dot Inks for Near to Short-Wave Infrared Detection

Article Publication Date

11-Sep-2025

 

Ultra-processed foods linked to heightened disease activity in early multiple sclerosis, new study finds

Higher intake of ultra-processed foods (UPFs) may exacerbate disease activity in early multiple sclerosis (MS), according to new research presented at the 41st Congress of the European Committee for Treatment and Research in Multiple Sclerosis.

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(Barcelona, Spain, Thursday, 25 September 2025) Higher intake of ultra-processed foods (UPFs) may exacerbate disease activity in early multiple sclerosis (MS), according to new research presented at the 41st Congress of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS 2025).1

Researchers found that increased UPF consumption was linked to more frequent relapses and greater MRI-detected lesion activity, highlighting the potential role of diet as a complementary strategy in disease management.

The study, led by Dr Gloria Dalla Costa, analysed data from 451 patients with clinically isolated syndrome – the first clinical presentation of MS – who were enrolled in the BENEFIT trial and followed for up to five years. A previously validated metabolomic signature of UPF intake, comprising 39 plasma metabolites developed by Harvard colleagues, was applied to baseline plasma samples to calculate individual UPF scores.

While UPF scores were not associated with conversion to clinically definite MS, higher scores at baseline were linked to greater T1 hypointense lesion volume, indicative of more severe tissue damage, and lower neurological function scores. Over the five-year follow-up, participants in the highest UPF quartile experienced approximately 30% more relapses than those in the lowest quartile.

By two years, they also had a higher rate of new active lesions, representing ongoing inflammation, and a larger increase in T2 lesion volume, a marker of accumulating tissue changes. These associations remained significant after adjustment for age, sex, treatment allocation, baseline disease burden, BMI, vitamin D, and smoking.

“This pattern suggests ultra-processed foods act as a chronic inflammatory accelerant rather than a disease trigger, amplifying existing inflammatory processes in MS rather than determining whether someone develops the disease in the first place,” said Dr Dalla Costa.

“The biological mechanisms behind this effect may involve disruption of the gut barrier by additives such as emulsifiers and preservatives, which can allow bacterial endotoxins to enter the bloodstream and trigger immune activation that reaches the brain,” she explained. “Elevated ceramides and modified lipids suggest UPF consumption may also alter membrane composition, making myelin – the insulating layer that forms around nerves – and the cells that produce it more vulnerable to autoimmune attack.”

“In addition, metabolic stress signatures such as elevated C4-OH carnitine point to impaired cellular energy production, limiting the brain’s ability to withstand and repair damage during inflammatory episodes. Overall, our findings suggest UPF consumption creates a cascade of biological disruptions that amplify MS inflammatory activity.”

Discussing the clinical implications of the findings, Dr Dalla Costa said, “I would recommend UPF reduction as a valuable supporting strategy for early MS management. Similar to vitamin D supplementation or smoking cessation advice, this is not about replacing established therapies, but about complementing them. It’s a low-risk, potentially high-benefit intervention.”

Looking ahead, the team plans to replicate these results in other MS cohorts, integrate microbiome analysis, and design intervention studies. “We are finalising a comprehensive manuscript which will provide the evidence base needed to inform clinical practice guidelines and establish the foundation for future dietary intervention studies,” Dr Dalla Costa concluded.

 

ENDS

About ECTRIMS 2025:

ECTRIMS 2025 – held on 24-26 September at the CCIB Barcelona International Convention Center in Barcelona, Spain – is the premier meeting place for researchers, clinicians and healthcare providers to collaborate on life-changing research and treatment options for people with MS and related diseases. This year’s programme offers top-tier scientific sessions, education, networking, and more.

Discover more: https://ectrims.eu/ectrims2025

About the study author:

Dr Gloria Dalla Costa is a neurologist and researcher at the Harvard T.H. Chan School of Public Health, Boston, USA, with extensive experience in multiple sclerosis clinical trials and patient care.

References:

1. Dalla Costa G. Association of Ultra-Processed Food Intake with Increased MS Disease Activity: Findings from the BENEFIT Trial. Presented at ECTRIMS 2025, Barcelona, Spain.

Longer body size means more female calves for baleen whale moms

University of Washington

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Long baleen whale mothers are more likely to have female calves than males, according to a new study led by the University of Washington. The findings contradict a popular evolutionary theory postulating that strong mammals benefit more from birthing males. 

In 1973, Robert Trivers and Dan Willard proposed that fit female mammals can improve their odds for grandchildren by having males. Large strong mothers will raise large strong calves that can outcompete other males for mates. But, according to the theory, female fitness is less consequential. The studies backing this argument focused on land mammals, such as deer and elk, and often included just tens or hundreds of animals. 

UW researchers tested the theory in marine mammals by comparing maternal length and fetal sex in more than 100,000 baleen whales. They found that the fetal sex ratio skews female for longer — and thus more fit — rorqual whales, the predominant baleen whale family that includes humpbacks and blue whales. The findings suggest that female calves benefit more from heritable fitness than males do.

Carrying and caring for young is exhausting, and whales often breed far from food sources. They must rely on stored fat to sustain themselves and their young during and after pregnancy. The results were published in Proceedings of the Royal Society B on Sept. 24.

“The question we wanted to answer was: if you are in good condition, if you’re big and fat and you’re going to have a big fat calf that will survive and reproduce — do you want that calf to be a male or a female?” said Zoe Rand, a UW doctoral student of quantitative ecology and resource management.  

To answer this question, the researchers turned to historical whaling data. 

Back in the early 1900s, when people hunted whales, a group from Norway began collecting data on their catch. The practice was codified into a law that required all Norwegian hunters to record the whale’s length, sex and pregnancy status, as well as the sex and size of a fetus. In the 1930s, the Norwegian regulation became international law.

“When they hunted whales, there were often biologists around who were knee-deep in the carcasses, measuring and collecting samples,”  Rand said. The International Whaling Commission banned whaling in 1986 to protect dwindling populations from further decimation. The IWC data, however, is a treasure trove for researchers. 

“We have this enormous data set with hundreds of thousands of data points that doesn’t exist for almost any other wild population,” said Trevor Branch, a UW professor in the School of Aquatic and Fisheries Sciences. In 2023, Branch created an interactive map depicting whale distribution from the data. 

The data also gave Rand an opportunity to investigate fetal sex ratios in marine mammals. Experts argue that some animals can influence the sex of their offspring just after conception. No one knows exactly how this works for mammals, but adapting sex ratios based on physical or environmental conditions is considered advantageous. 

“I think for our mammal brains, it is a little bit confusing,” Rand said, “But insects, like bees and ants, have a lot of control over the sex of their offspring, so it’s not entirely surprising that mammals might have a little bit of control.” 

In this study, the researchers modeled maternal length against sex for fetuses measuring three feet and longer — the size at which sex becomes evident. They included seven whale species in the rorqual family, totalling more than 100,000 whales.

If the Trivers-Willard hypothesis were correct, researchers would have seen a slight increase in the number of male fetuses as maternal length increased. Instead, they observed a downward trend, indicating that fewer males were born to larger mothers. The results varied some by species: Longer female humpbacks were 77% more likely to have a female calf, and that probability increased to 99% for sei whales.

There are several possible explanations for why these findings flip the Trivers-Willard hypothesis, and the trends observed in land mammals. Some male whales compete for mates, but competition might not be as significant a pressure as female size because small female whales will likely struggle to reproduce and raise healthy young. Big whales, on the other hand, will have big female calves that will grow into long mothers with strong reproductive potential. 

For baleen whale mothers, investing energy in female calves is the best way to ensure generations of grandchildren. 

Research also suggests that many whale species are getting smaller, which could spell trouble for future generations if females are unable to support offspring. The findings could have implications for conservation, but Rand said that this will require further research to confirm.

“Previously it was assumed that if you have male-male competition for mates, bigger mothers will have males,”  Rand said. “Our paper shows that you can’t make that assumption because there’s also an advantage to being big as a female.” 

Other authors include Sarah J. Converse, the Leader of the USGS Washington Cooperative Fish and Wildlife Research Unit and a Professor in the UW School of Aquatic and Fishery Sciences.

This research was funded by the National Oceanic and Atmospheric Administration.

Contact Rand at zrand@uw.edu for more information.

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Journal

Proceedings of the Royal Society B Biological Sciences

DOI

10.1098/rspb.2025-1427 

Method of Research

Data/statistical analysis

Subject of Research

Animals

Article Title

Longer rorqual whale mothers produce more female offspring

Article Publication Date

24-Sep-2025