Rising Autism - Longer fMRI - Big Thumbs = Big Brains? - Cat Alzheimer's

[Breedlove, S]

https://www.nature.com/articles/d41586-025-02636-1

Autism is on the rise: what’s really behind the increase?

    Helen Pearson 

On 16 April, Robert F. Kennedy Jr held a press conference about rising diagnoses of autism. The US Health and Human Services (HHS) secretary pointed to new data showing that autism prevalence in the United States had risen steeply from one in 150 eight-year-olds in 2000 to one in 31 in 2022. He called it an “epidemic” caused by “an environmental toxin” — and said he would soon be announcing a study to find the responsible agent.

The next month, the US National Institutes of Health (NIH), part of the department that Kennedy leads, announced the Autism Data Science Initiative (ADSI). The initiative offered up to US$50 million to fund studies on the causes of autism. The winning applications are expected to be announced in September.

Usually, big investments in research are welcomed by scientists — but not this time. Many were dismayed that these developments seemed to ignore decades of work on the well-documented rise in autism diagnoses and on causes of the developmental condition. Although Kennedy said that environmental factors are the main cause of autism, research has shown that genetics plays a bigger part. Population studies1 have linked a handful of environmental factors — mostly encountered during pregnancy — to increased chances of autism, but their precise role has been hard to pin down. More than anything, research has shown that the drivers of autism are fiendishly complicated. “There will never be a sound-bite answer to what causes autism,” says Helen Tager-Flusberg, a psychologist who studies neurodevelopmental conditions at Boston University, Massachusetts.

The rise in prevalence, many researchers say, is predominantly caused by an increase in diagnoses rather than a true rise in the underlying symptoms and traits. “We don’t see an epidemic of autism, but we see an ‘epidemic’ of diagnoses,” says Sven Bölte, a specialist in child and adolescent psychiatric science at the Karolinska Institute in Stockholm. Researchers are concerned that Kennedy, an anti-vaccine advocate, will use the ADSI to promote the disproven idea that vaccines are linked to autism.

© 2025 Springer Nature Limited

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https://undark.org/2025/08/27/podcast-autism-research/

Should We Try to Prevent Autism?

Welcome to Entanglements. In this episode, hosts Brooke Borel and Anna Rothschild ask: Should we try to prevent autism? It’s a question that has divided the autistic community, and the answer has significant implications on how to focus scientific research and funding.

Their guests this week are Jill Escher, a philanthropist, president of the National Council on Severe Autism, and parent of two young adults with severe nonverbal autism, and Eric García, the Washington bureau chief at The Independent and the author of “We’re Not Broken: Changing the Autism Conversation,” who is himself autistic. 

Robert F. Kennedy Jr: These are kids who will never pay taxes, they’ll never hold a job, they’ll never play baseball, they’ll never write a poem, they’ll never go out on a date. Many of them will never use a toilet unassisted. And we have to recognize we are doing this to our children.

Anna Rothschild: That was Health and Human Services Secretary Robert F. Kennedy Jr., talking about autism back in April of 2025. And he promised to find some answers about the cause of the condition, which he called an epidemic.

Robert F. Kennedy Jr: This is a preventable disease. We know it’s an environmental exposure. It has to be. Genes do not cause epidemics.

Anna Rothschild: On that note, welcome to Entanglements, the show where we wade into the murkiest scientific controversies and search for common ground. I’m science journalist Anna Rothschild.

Brooke Borel: And I’m Brooke Borel, articles editor at Undark Magazine. And that was a dramatic cold open. Anna, what’s happening here? Are you about to do an episode on whether vaccines cause autism?

Anna Rothschild: No, that is not a murky controversy. That has been rigorously disproven.

Brooke Borel: Yeah.

Anna Rothschild: No, today we are asking the question: Should we try to prevent autism?
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https://www.thetransmitter.org/fmri/longer-fmri-brain-scans-boost-reliability-but-only-to-a-point/

 Longer fMRI brain scans boost reliability—but only to a point

By Claudia López Lloreda

fMRI researchers have long faced a conundrum: Given finite resources and time to spend on scanning, is it better to scan lots of participants for a short time each, or a smaller number of people for a longer time?

A new study quantifies this tradeoff for brain-wide association studies (BWAS), which aim to link brain differences to physical and cognitive traits. Using large-scale public fMRI datasets, the team found that their ability to accurately predict cognitive features from functional connectivity data increased with sample size and with scan length, up to 20 minutes. But accuracy began to plateau for longer scans, and beyond 30 minutes, the added length (and cost) provided diminishing returns.

A half-hour seems to be the optimal scanning time, says Thomas Yeo, associate professor of electrical and computer engineering at the National University of Singapore and principal investigator of the study. Scan duration is “essentially providing a different knob for people to tune” to meet power requirements in their fMRI experiments, he says.

Although the neuroimaging community already knew that scan time is important and five minutes is insufficient, “this is one of the first major studies in the past few years to really quantitatively map that out” for BWAS studies, says Brenden Tervo-Clemmens, assistant professor of psychiatry and behavioral sciences at the University of Minnesota, who was not involved with the study. Tervo-Clemmens and his colleagues had previously shown in a 2022 study the importance of sample size in BWAS, calculating that these analyses need thousands of participants to get meaningful associations. This new study adds another part of the equation, he says.

Yeo’s team developed the Optimal Scan Time Calculator to help other neuroscientists design their own studies. “Democratizing these complex methodological issues into a usable package is really, really useful,” Tervo-Clemmens says.

© 2025 Simons Foundation
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https://www.theguardian.com/science/2025/aug/26/primates-with-longer-thumbs-tend-to-have-bigger-brains-research-finds

Primates with longer thumbs tend to have bigger brains

Nicola Davis Science correspondent

Big hands might mean big feet, but it seems long thumbs are linked to large brains – at least in primates.

Researchers say the results suggest the brain co-evolved with manual dexterity in such mammals.

“We imagine an evolutionary scenario in which a primate or human has become more intelligent, and with that comes the ability to think about action planning, think about what you are doing with your hands, and realise that actually you are more efficient at doing it one way or another,” said Dr Joanna Baker, lead author of the research from the University of Reading.

“And those that have longer thumbs or more ability to manipulate the objects in the way that the mind can see were likely to be more successful.”

Large brains and manual dexterity are both thought to have played an important role in human evolution, with opposable thumbs a key feature that enabled a greater ability to grip and manipulate items – including tools.

However, with some other primates having partly opposable thumbs, questions have remained over whether other changes in the hand – such as thumb length – could also be important in the evolution of tool use.

“In general terms, you can say that the longer the thumb you have, the more motion you have to pick up and control small objects,” said Baker.

To explore the issue Baker and colleagues studied the estimated brain mass and thumb length of 94 primate species, from five of our ancient hominin relatives to lemurs.

The results, published in the journal Communications Biology, reveal humans and most other hominins have thumbs that are significantly longer than would be predicted based on the hand proportions of primates as a while. However, further analysis revealed an intriguing pattern.

“When you have longer thumbs relative to your overall hand, that tends to come in conjunction with overall increased brain size,” said Baker.
© 2025 Guardian News & Media Limited
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https://www.sciencenews.org/article/cat-dementia-clues-alzheimers-brain

 Elderly cats with dementia may hold clues for Alzheimer’s

By Claudia López Lloreda

As cats age, they may yowl more than usual at night, have trouble sleeping or sleep too much, and act generally confused or disoriented. Now a new study shows that, just like in humans with Alzheimer’s disease, amyloid-beta plaques build up in the brains of aging felines and may contribute to dementia-like behaviors.

In cats, that buildup could be causing a cascade of problems within the brain, such as hyperactivation of immune and other supporting brain cells that attack the synapses that connect nerve cells, researchers report August 11 in European Journal of Neuroscience. Aged cats with and without dementia had similar features and only a small number of cats were studied. But these findings could start helping researchers better understand how cats age and potentially develop treatments for feline dementia, as well as provide new insights into how the disease progresses in humans.

Earlier studies had found amyloid beta in the brains of cats, but scientists didn’t know to what extent it was disrupting brain function. Robert McGeachan, a veterinarian at the University of Edinburgh, knew that the number of synapses decreased early in Alzheimer’s disease in humans. And so he and his team decided to focus on these connections in their cat study. They looked at the postmortem brains of seven young cats and 18 older ones, including eight with behavioral signs of dementia.

Using fluorescent markers that find and cling to amyloid beta, the team found that the brains of aged cats, with or without dementia, had more of the protein than the younger brain samples. The amyloid beta plaques in the older cats also tended to accumulate right around synapses.

© Society for Science & the Public 2000–2025. 
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