Puberty & Brain Sex - Mental Exercise & Alzheimer's - DMT & Depression - Species Problem

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Feb 18, 2026, 6:24:30 AM (6 days ago) Feb 18

https://www.nature.com/articles/d41586-026-00349-7

Brain differences between sexes get more pronounced from puberty

By Chris Simms

Some sex differences in brain-connectivity patterns become more pronounced with age, according to new research.

Researchers studying brain-imaging data from people aged between 8 and 100 found that sex differences in the brain’s connections are minimal in early life, but then increase drastically at puberty; some of these differences continue to grow throughout adult life. The study was published as a preprint on bioRxiv1, and has not yet been peer reviewed.

The work could help us to understand why men and women have different likelihoods of developing some mental-health disorders — and perhaps give insight into treating them, say the researchers. For example, women are about twice as likely as men to develop anxiety or depression2, and boys are about four times more likely to be diagnosed with autism spectrum disorder than girls3.

“We are very excited about this study, which to our knowledge is the first one to compare how sex differences in brain networks evolve over the lifespan,” says Amy Kuceyeski, a computational neuroimager at Weill Cornell Medicine in Ithaca, New York.

However, some neuroscientists who spoke to Nature aren’t convinced that the differences found between male and female brains are due to sex, and say the study does not address differences in gender roles, which are known to be important factors when researching brain mechanisms of health and disease.

Human brains do not belong in distinct ‘female’ and ‘male’ categories, says Daphna Joel, a neuroscientist at the University of Tel Aviv in Israel, referring to a 2015 study she co-authored, which suggests that each human brain is a mosaic of features, some of which are more common in men, others in women4.

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https://www.npr.org/2026/02/18/nx-s1-5716010/brain-training-exercise-cut-dementia-risk-decades

This form of mental exercise may cut dementia risk for decades

Jon Hamilton

A little brain training today may help stave off Alzheimer's disease and other forms of dementia for at least 20 years.

That's the conclusion of a study of older adults who participated in a cognitive exercise experiment in the 1990s that was designed to increase the brain's processing speed.

The federally funded study of 2,802 people found that those who did eight to 10 roughly hourlong sessions of cognitive speed training, as well as at least one booster session, were about 25% less likely to be diagnosed with dementia over the next two decades.

"We now have a gold-standard study that tells us that there is something we can do to reduce our risk for dementia," says Marilyn Albert, an author of the study and a professor of neurology at Johns Hopkins University School of Medicine.

"It's super-exciting to see that these effects are still holding 20 years out," says Jennifer O'Brien, an associate professor of psychology at the University of South Florida who was not involved in the research.

The study appears in the journal Alzheimer's & Dementia: Translational Research & Clinical Interventions.

The result is good news for people like George Kovach, 74, who started doing cognitive speed training a decade ago.
This illustration shows a pink human brain with stick legs and stick arms. The pink stick arms are holding up a black barbell with black disk-shaped weights on each end.
© 2026 npr

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https://www.theguardian.com/science/2026/feb/16/psychedelic-drug-dmt-treat-depression-trial-shows

Single dose of potent psychedelic drug could help treat depression

Ian Sample Science editor

People with major depressive disorder can see a rapid and lasting improvement after a single dose of the psychedelic drug dimethyltryptamine (DMT) when it is combined with psychotherapy, doctors have said.

A small clinical trial involving 34 people found that psychedelic-assisted therapy prompted a swift reduction in depressive symptoms that endured long after the drug had worn off, with some still feeling the benefits six months later.

“There is an immediate antidepressant effect that is significantly sustained over a three-month period and that’s exciting because this is one session with a drug, embedded in psychological support,” said Dr David Erritzoe, a psychiatrist at Imperial College London and lead investigator on the trial.

Although preliminary, the results add to a growing body of evidence that psychedelic drugs, when coupled with psychotherapy, could help to alleviate depression in the millions of people worldwide who do not respond to existing antidepressants or therapies.

An estimated 100 million people worldwide have treatment-resistant depression, defined as a major depressive disorder that has not responded to at least two antidepressants. About half are unable to perform routine daily tasks.

The trial, reported in Nature Medicine, focused on people with moderate to severe treatment-resistant depression. One half received a single 21.5mg dose of DMT infused into a vein over 10 minutes. The other half received a placebo infused the same way. All of the participants had psychotherapy and follow-up assessments.

https://www.nytimes.com/2026/02/14/science/tortoises-island-sex-cliff.html

Constant Sexual Aggression Drives Female Tortoises to Walk Off Cliffs

By Elizabeth Preston

On the island of Golem Grad in North Macedonia, visitors may see a chain of tortoises mounting each other like a slow-moving, libidinous locomotive. It used to strike Dragan Arsovski, an ecologist at the Macedonian Ecological Society, as funny. Now that he knows what’s really going on, he isn’t laughing.

This uninhabited island in a country that once was part of Yugoslavia is crawling with around 1,000 Hermann’s tortoises — especially males. They pursue mates aggressively, making life unhealthy and short for the island’s scarce females. Some of those females even die by walking off the island’s cliffs. In a paper published last month in the journal Ecology Letters, researchers have found that the relentless males are driving their population to extinction.

The island, in Lake Prespa, has a forested plateau encircled by sheer cliffs. When Dr. Arsovski started studying the salad-plate-size tortoises in 2008, “it was quite a dense and seemingly prosperous population,” he said.

But for some reason, there were far more adult males than females — 19 males for every female on the plateau, at the latest count. He and his colleagues documented how the males seemed to manage their carnal instincts by mounting each other.

Then, after many years of study, Dr. Arsovski realized that the females were undersized and dying young. He also realized those once-comical copulatory trains were made up of many males pursuing just one female. When the female tired, the train would become a frenzied heap of reptiles. “She’s literally buried by males,” Dr. Arsovski said.

He and his co-authors wrote that as part of the tortoises’ courtship, they “bump, bite (sometimes to the point of blood loss), mount and finally vigorously poke fleeing females” with a sharp tail tip. Three-quarters of the island’s females had genital injuries.

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https://www.thetransmitter.org/animal-models/neuroscience-has-a-species-problem/

Neuroscience has a species problem

By Nanthia Suthana

Neuroscience has never been richer in data. Laboratories now generate detailed recordings of neural activity, behavior and physiology across species at scales unimaginable a decade ago. In rodents, researchers can monitor thousands of neurons simultaneously across distributed circuits during behavior. In humans, they can record from deep brain structures during ambulatory, real-world behavior, integrated with wearable sensors and linked to clinical symptoms and subjective experience. The field has access to neural signals spanning orders of magnitude in space, time and biological complexity.

Yet despite this abundance, neuroscience remains deeply organized along species lines. Animal and human researchers often operate within separate conceptual frameworks, attend different conferences and develop theories that rarely confront data across species. This separation is no longer a minor inconvenience but a growing liability. The problem is not simply that cross-species translation is difficult; it is that the field has largely accepted this difficulty rather than treating it as a central scientific challenge. Neuroscience has also struggled to confront the fact that different species often tell different stories.

As a result, neuroscience’s primary limitation today is not a lack of data or tools, but persistent fragmentation across model systems, recording modalities and analytic traditions. Findings are typically interpreted within species- and technique-specific frameworks, with little pressure to explain when, how or why neural principles should generalize across organisms. Researchers acknowledge differences but rarely use them to constrain or revise theory.