Tagged Brain

Hypertension During Pregnancy Tied to Later Cognitive Decline

Hypertension During Pregnancy Tied to Later Cognitive Decline

Pregnant women with blood pressure readings above 140/90 had deficits on tests of mental agility 15 years later.

Nicholas Bakalar

  • Jan. 20, 2021, 2:46 p.m. ET

Women who develop gestational hypertension — high blood pressure during pregnancy — may have reduced cognitive abilities later in life, a recent report suggests.

The study, in Neurology, included 115 women with a history of gestational hypertension between 2002 and 2006. They measured their mental agility an average of 15 years later using well-validated tests of verbal fluency, processing speed, memory and visuospatial skills. Then they compared their results with those of 481 women whose blood pressure remained normal during their pregnancies.

After controlling for ethnicity, educational level, pre-pregnancy B.M.I. and other factors, they found that women who were hypertensive during pregnancy had significantly lower scores on tests of working memory and verbal learning than those whose blood pressure was normal.

The lead author, Dr. Maria C. Adank, a researcher at Erasmus University in Rotterdam, pointed out that the effect was driven mainly by the 70 percent of women in the study who had only mild hypertension — readings above 140/90 — and not by the 30 percent who had pre-eclampsia, the extremely high blood pressure that, untreated, can lead to organ damage and death in both mothers and babies.

“These are women with only mild hypertension. They’re healthy. But even at age 45 they have impaired cognition,” she said. “They and their clinicians should be aware of the risk, and they should be followed up. We think that hypertension is going to persist beyond pregnancy, and it should be treated.”

Small Number of Covid Patients Develop Severe Psychotic Symptoms

Small Number of Covid Patients Develop Severe Psychotic Symptoms

Most had no history of mental illness and became psychotic weeks after contracting the virus. Cases are expected to remain rare but are being reported worldwide.

Dr. Hisam Goueli treated several psychotic patients who had never had mental health issues before, including a woman who told him she kept visualizing her children being murdered. “It was like she was experiencing a movie,” he said.
Dr. Hisam Goueli treated several psychotic patients who had never had mental health issues before, including a woman who told him she kept visualizing her children being murdered. “It was like she was experiencing a movie,” he said.Credit…Jovelle Tamayo for The New York Times
Pam Belluck

  • Dec. 28, 2020, 12:03 p.m. ET

Almost immediately, Dr. Hisam Goueli could tell that the patient who came to his psychiatric hospital on Long Island this summer was unusual.

The patient, a 42-year-old physical therapist and mother of four young children, had never had psychiatric symptoms or any family history of mental illness. Yet there she was, sitting at a table in a beige-walled room at South Oaks Hospital in Amityville, N.Y., sobbing and saying that she kept seeing her children, ages 2 to 10, being gruesomely murdered and that she herself had crafted plans to kill them.

“It was like she was experiencing a movie, like ‘Kill Bill,’” Dr. Goueli, a psychiatrist, said.

The patient described one of her children being run over by a truck and another decapitated. “It’s a horrifying thing that here’s this well-accomplished woman and she’s like ‘I love my kids, and I don’t know why I feel this way that I want to decapitate them,’” he said.

The only notable thing about her medical history was that the woman, who declined to be interviewed but allowed Dr. Goueli to describe her case, had become infected with the coronavirus in the spring. She had experienced only mild physical symptoms from the virus, but, months later, she heard a voice that first told her to kill herself and then told her to kill her children.

At South Oaks, which has an inpatient psychiatric treatment program for Covid-19 patients, Dr. Goueli was unsure whether the coronavirus was connected to the woman’s psychological symptoms. “Maybe this is Covid-related, maybe it’s not,” he recalled thinking.

“But then,” he said, “we saw a second case, a third case and a fourth case, and we’re like ‘There’s something happening.’”

Indeed, doctors are reporting similar cases across the country and around the world. A small number of Covid patients who had never experienced mental health problems are developing severe psychotic symptoms weeks after contracting the coronavirus.

In interviews and scientific articles, doctors described:

A 36-year-old nursing home employee in North Carolina who became so paranoid that she believed her three children would be kidnapped and, to save them, tried to pass them through a fast-food restaurant’s drive-through window.

A 30-year-old construction worker in New York City who became so delusional that he imagined his cousin was going to murder him, and, to protect himself, he tried to strangle his cousin in bed.

A 55-year-old woman in Britain had hallucinations of monkeys and a lion and became convinced a family member had been replaced by an impostor.

Beyond individual reports, a British study of neurological or psychiatric complications in 153 patients hospitalized with Covid-19 found that 10 people had “new-onset psychosis.” Another study identified 10 such patients in one hospital in Spain. And in Covid-related social media groups, medical professionals discuss seeing patients with similar symptoms in the Midwest, Great Plains and elsewhere.

“My guess is any place that is seeing Covid is probably seeing this,” said Dr. Colin Smith at Duke University Medical Center in Durham, who helped treat the North Carolina woman. He and other doctors said their patients were too fragile to be asked whether they wanted to be interviewed for this article, but some, including the North Carolina woman, agreed to have their cases described in scientific papers.

Medical experts say they expect that such extreme psychiatric dysfunction will affect only a small proportion of patients. But the cases are considered examples of another way the Covid-19 disease process can affect mental health and brain function.

Although the coronavirus was initially thought primarily to cause respiratory distress, there is now ample evidence of many other symptoms, including neurological, cognitive and psychological effects, that could emerge even in patients who didn’t develop serious lung, heart or circulatory problems. Such symptoms can be just as debilitating to a person’s ability to function and work, and it’s often unclear how long they will last or how to treat them.

Experts increasingly believe brain-related effects may be linked to the body’s immune system response to the coronavirus and possibly to vascular problems or surges of inflammation caused by the disease process.

“Some of the neurotoxins that are reactions to immune activation can go to the brain, through the blood-brain barrier, and can induce this damage,” said Dr. Vilma Gabbay, a co-director of the Psychiatry Research Institute at Montefiore Einstein in the Bronx.

Brain scans, spinal fluid analyses and other tests didn’t find any brain infection, said Dr. Gabbay, whose hospital has treated two patients with post-Covid psychosis: a 49-year-old man who heard voices and believed he was the devil and a 34-year-old woman who began carrying a knife, disrobing in front of strangers and putting hand sanitizer in her food.

Physically, most of these patients didn’t get very sick from Covid-19, reports indicate. The patients that Dr. Goueli treated experienced no respiratory problems, but they did have subtle neurological symptoms like hand tingling, vertigo, headaches or diminished smell. Then, two weeks to several months later, he said, they “develop this profound psychosis, which is really dangerous and scary to all of the people around them.”

Also striking is that most patients have been in their 30s, 40s and 50s. “It’s very rare for you to develop this type of psychosis in this age range,” Dr. Goueli said, since such symptoms more typically accompany schizophrenia in young people or dementia in older patients. And some patients — like the physical therapist who took herself to the hospital — understood something was wrong, while usually “people with psychosis don’t have an insight that they’ve lost touch with reality.”

Some post-Covid patients who developed psychosis needed weeks of hospitalization in which doctors tried different medications before finding one that helped.

Dr. Robert Yolken, a neurovirology expert at Johns Hopkins University School of Medicine in Baltimore, said that although people might recover physically from Covid-19, in some cases their immune systems, might be unable to shut down or might remain engaged because of “delayed clearance of a small amount of virus.”

Persistent immune activation is also a leading explanation for brain fog and memory problems bedeviling many Covid survivors, and Emily Severance, a schizophrenia expert at Johns Hopkins, said post-Covid cognitive and psychiatric effects might result from “something similar happening in the brain.”

It may hinge on which brain region the immune response affects, Dr. Yolken said, adding, “some people have neurological symptoms, some people psychiatric and many people have a combination.”

From left, Drs. Jonathan Komisar, Brian Kincaid and Colin Smith of Duke University Medical Center, who treated a woman whose sudden psychosis made her paranoid that her children were about to be kidnapped and that cellphones were tracking her.
From left, Drs. Jonathan Komisar, Brian Kincaid and Colin Smith of Duke University Medical Center, who treated a woman whose sudden psychosis made her paranoid that her children were about to be kidnapped and that cellphones were tracking her.Credit…Jeremy M. Lange for The New York Times

Experts don’t know whether genetic makeup or perhaps an undetected predisposition for psychiatric illness put some people at greater risk. Dr. Brian Kincaid, medical director of psychiatric emergency department services at Duke, said the North Carolina woman once had a skin reaction to another virus, which might suggest her immune system responds zealously to viral infections.

Sporadic cases of post-infectious psychosis and mania have occurred with other viruses, including the 1918 flu and the coronaviruses SARS and MERS.

“We think that it’s not unique to Covid,” said Dr. Jonathan Alpert, chairman of psychiatry and behavioral sciences at Albert Einstein College of Medicine, who co-wrote the report on the Montefiore patients. He said studying these cases might help to increase doctors’ understanding of psychosis.

The symptoms have ranged widely, some surprisingly severe for a first psychotic episode, experts said. Dr. Goueli said a 46-year-old pharmacy technician, whose family brought her in after she became fearful that evil spirits had invaded her home, “cried literally for four days” in the hospital.

He said the 30-year-old construction worker, brought to the hospital by the police, became “extremely violent,” dismantling a hospital radiator and using its parts and his shoes to try to break out of a window. He also swung a chair at hospital staff.

How long the psychosis lasted and patients’ response to treatment has varied. The woman in Britain — whose symptoms included paranoia about the color red and terror that nurses were devils who would harm her and a family member — took about 40 days to recover, according to a case report.

The 49-year-old man treated at Montefiore was discharged after several weeks’ hospitalization, but “he was still struggling two months out” and required readmission, Dr. Gabbay said.

The North Carolina woman, who was convinced that cellphones were tracking her and that her partner would steal her pandemic stimulus money, didn’t improve with the first medication, said Dr. Jonathan Komisar at Duke, who said doctors initially thought her symptoms reflected bipolar disorder. “When we began to realize that maybe this isn’t going resolve immediately,” he said, she was given an antipsychotic, risperidone and discharged in a week.

The physical therapist who planned to murder her children had more difficulty. “Every day, she was getting worse,” Dr. Goueli said. “We tried probably eight different medicines,” including antidepressants, antipsychotics and lithium. “She was so ill that we were considering electroconvulsive therapy for her because nothing was working.”

About two weeks into her hospitalization, she couldn’t remember what her 2-year-old looked like. Calls with family were heartbreaking because “‘You could hear one in the background saying ‘When is Mom coming home?’” Dr. Goueli said. “That brought her a lot of shame because she was like, ‘I can’t be around my kids and here they are loving me.’”

Ultimately, risperidone proved effective and after four weeks, she returned home to her family, “95 percent perfect,” he said.

“We don’t know what the natural course of this is,” Dr. Goueli said. “Does this eventually go away? Do people get better? How long does that normally take? And are you then more prone to have other psychiatric issues as a result? There are just so many unanswered questions.”

Covid 'Long-Haulers' Need Medical Attention, Experts Urge

Covid Survivors With Long-Term Symptoms Need Urgent Attention, Experts Say

In a two-day meeting sponsored by the N.I.H., officials acknowledged an insufficient understanding of the issues and warned of a growing public health problem.

Chimére Smith, a teacher in Baltimore, has not been able to return to work since getting Covid in March. She said she has struggled for months to have her symptoms taken seriously by doctors.
Chimére Smith, a teacher in Baltimore, has not been able to return to work since getting Covid in March. She said she has struggled for months to have her symptoms taken seriously by doctors.Credit…Schaun Champion for The New York Times
Pam Belluck

By

  • Dec. 4, 2020, 12:06 p.m. ET

There is an urgent need to address long-term symptoms of the coronavirus, leading public health officials said this week, warning that hundreds of thousands of Americans and millions of people worldwide might experience lingering problems that could impede their ability to work and function normally.

In a two-day meeting Thursday and Friday, the federal government’s first workshop dedicated to long-term Covid-19, public health officials, medical researchers and patients said the condition needed to be recognized as a syndrome, given a name and taken seriously by doctors.

“This is a phenomenon that is really quite real and quite extensive,” Dr. Anthony S. Fauci, the nation’s top infectious diseases expert, said at the conference on Thursday.

While the number of people affected is still unknown, he said, if long-term symptoms afflict even a small proportion of the millions of people infected with the coronavirus, it is “going to represent a significant public health issue.”

Such symptoms — ranging from breathing trouble to heart issues to cognitive and psychological problems — are already plaguing an untold number of people worldwide. Even for people who were never sick enough to be hospitalized, the aftermath can be long and grueling with a complex and lasting mix of symptoms.

The Centers for Disease Control and Prevention recently posted a list of some long-term symptoms, including fatigue, joint pain, chest pain, brain fog and depression, but doctors and researchers said they still know little about the extent or cause of many of the problems, which patients will develop them or how to address them.

Over the last several months, coronavirus patients with lingering, debilitating health issues have been widely referred to as “Covid long-haulers.” But some survivors and experts feel that name trivializes the experience, lessening its importance as a medical syndrome which doctors and insurers should recognize, diagnose and try to treat. One of the pressing issues patients and experts are now weighing is what official medical term should be adopted to describe the collection of post-Covid symptoms.

“We need to dig in and do the work that needs to be done to help relieve the suffering and stop this madness,” said Dr. Michael Haag, an infectious disease expert from the University of Alabama at Birmingham, who was a co-chair of a session.

In an inadvertent but stark illustration of the difficulty of the recovery process, two of the four patients scheduled to speak at the meeting were unable to because they had recently been rehospitalized. “Those individuals had their acute illness several months ago and they’ve been suffering pretty mightily since then,” Dr. Haag said. “And the fact that they’re still struggling with this gives extra power to what we’re trying to do today.”

Dr. John Brooks, the chief medical officer of the C.D.C.’s Covid response, the co-chairman with Dr. Haag of one session, said he expected long-term post-Covid symptoms would affect “on the order of tens of thousands in the United States and possibly hundreds of thousands.”

He added, “If you were to ask me what do we know about this post-acute phase, I really am hard pressed to tell you that we know much. This is what we’re really working on epidemiologically to understand what is it, how many people get it, how long does it last, what causes it, who does it affect, and then of course, what can we do to prevent it from happening.”

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Presentations from Covid-19 survivors — including Dr. Peter Piot, a world-renowned infectious disease expert who helped discover the Ebola virus — made it clear that for many people, recovering from the disease is not like flipping a switch.

Dr. Piot, who is the director of the London School of Hygiene and Tropical Medicine and a special adviser on Covid-19 research to the president of the European Commission, said he contracted the coronavirus in March and was hospitalized for a week in April. The acute phase of his illness involved some, but not all, of the classic disease symptoms. For example, his oxygen saturation was very low, but he did not develop shortness of breath or a cough until after he got home from the hospital.

For the next month, he experienced a rapid heart rate several hours a day, he said. For nearly four months, he experienced extreme fatigue and insomnia. “What I found most frustrating personally was that I couldn’t do anything,” said Dr. Piot, who now considers himself recovered except for needing more sleep than before his infection. “I just had to wait for improvement.”

Chimére Smith, 38, a teacher in Baltimore who has not been able to work since becoming sick in March, said she had struggled for months to have her symptoms, which included loss of vision in one eye, taken seriously by doctors.

“It’s been a harrowing task and the task and the journey continues,” she said.

Ms. Smith, who is Black, said it was especially important to inform people in underserved communities that long-term effects are “as real and possible as dying from the virus itself.”

The condition, she said, “not only needs to be explored, but it needs to be explained to the same group of people who suffer with being stricken with it the most, and that’s the minority population. I am not just here today for me; I am here for us.”

Hannah Davis, 32, a researcher and artist in Brooklyn, described neurological and cognitive symptoms that began in late March. “I forgot my partner’s name,” she said. “I forgot about sleep. I would regularly pick up a hot pan, burn myself, put it down, and literally do it again. I forgot how to shower. I forgot how to dress myself.”

Months later, some things have improved, but she still struggles to remember things, saying “I feel like I am basically on a 48-hour memory cycle.”

Ms. Davis is part of a long-term Covid survivor group called Body Politic and said a survey of 3,800 of its members in 56 countries has found that 85 percent report cognitive dysfunction, 81 percent had numbness and other neurological sensations, nearly half had speech and language issues and nearly three-quarters had some difficulty working at their jobs.

Clinics treating Covid survivors are seeing a striking number of people with brain fog and other thinking problems, as well as psychological issues, doctors participating in the workshop said.

“Approximately three months after their acute illness, more than half of our patients have at least a mild cognitive impairment,” said Dr. Ann Parker, who co-directs a post-Covid clinic at Johns Hopkins. “We’re also seeing substantial mental health impairments.”

Dr. Janet Diaz, head of clinical care for the World Health Organization’s Covid-19 response, said the agency is planning a meeting focused on long-term coronavirus effects and will soon start collecting data on post-Covid symptoms and medical visits.

She said that while doctors are accustomed to prolonged recovery challenges for people hospitalized for serious illnesses, the lingering symptoms in younger people and those who were not hospitalized for the coronavirus “urgently needs to be better understood and investigated.”

To Boost Memory: Study, Wait, Then Exercise

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Credit Illustration by Renaud Vigourt

Learning requires more than the acquisition of unfamiliar knowledge; that new information or know-how, if it’s to be more than ephemeral, must be consolidated and securely stored in long-term memory.

Mental repetition is one way to do that, of course. But mounting scientific evidence suggests that what we do physically also plays an important role in this process. Sleep, for instance, reinforces memory. And recent experiments show that when mice and rats jog on running wheels after acquiring a new skill, they learn much better than sedentary rodents do. Exercise seems to increase the production of biochemicals in the body and brain related to mental function.

Researchers at the Donders Institute for Brain, Cognition and Behavior at Radboud University in the Netherlands and the University of Edinburgh have begun to explore this connection. For a study published this month in Current Biology, 72 healthy adult men and women spent about 40 minutes undergoing a standard test of visual and spatial learning. They observed pictures on a computer screen and then were asked to remember their locations.

Afterward, the subjects all watched nature documentaries. Two-thirds of them also exercised: Half were first put through interval training on exercise bicycles for 35 minutes immediately after completing the test; the others did the same workout four hours after the test.

Two days later, everyone returned to the lab and repeated the original computerized test while an M.R.I. machine scanned their brain activity.

Those who exercised four hours after the test recognized and recreated the picture locations most accurately. Their brain activity was subtly different, too, showing a more consistent pattern of neural activity. The study’s authors suggest that their brains might have been functioning more efficiently because they had learned the patterns so fully. But why delaying exercise for four hours was more effective than an immediate workout remains mysterious. By contrast, rodents do better in many experiments if they work out right after learning.

Eelco van Dongen, the study’s lead author and a former researcher at Radboud University (he is now a policy officer at the Netherlands Organization for Scientific Research), hopes that future studies will help determine both the optimal time to exercise and the ideal activity to reinforce learning. Workouts that are too strenuous “could be less positive or even detrimental” to acquiring knowledge, Dr. van Dongen says, while gentle exertions — “a short, slow walk,” he adds — might not prompt enough of an increase in the biochemicals needed to influence how the brain learns.

For now, he says, if you are trying to memorize a PowerPoint narrative or teach yourself macroeconomics, it could be beneficial to exercise a few hours after a study session. “Long-term memory is not only influenced by what happens when you learn new things,” he says, “but also by the processes that take place in the hours and days afterward, when new information is stabilized and integrated in your brain.”

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Can Running Make You Smarter?

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Credit Getty Images

To strengthen your mind, you may first want to exert your leg muscles, according to a sophisticated new experiment involving people, mice and monkeys. The study’s results suggest that long-term endurance exercise such as running can alter muscles in ways that then jump-start changes in the brain, helping to fortify learning and memory.

I often have written about the benefits of exercise for the brain and, in particular, how, when lab rodents or other animals exercise, they create extra neurons in their brains, a process known as neurogenesis. These new cells then cluster in portions of the brain critical for thinking and recollection.

Even more telling, other experiments have found that animals living in cages enlivened with colored toys, flavored varieties of water and other enrichments wind up showing greater neurogenesis than animals in drab, standard cages. But animals given access to running wheels, even if they don’t also have all of the toys and other party-cage extras, develop the most new brain cells of all.

These experiments strongly suggest that while mental stimulation is important for brain health, physical stimulation is even more potent.

But so far scientists have not teased out precisely how physical movement remakes the brain, although all agree that the process is bogglingly complex.

Fascinated by that complexity, researchers at the National Institutes of Health recently began to wonder whether some of the necessary steps might be taking place far from the brain itself, and specifically, in the muscles, which are the body part most affected by exercise. Working muscles contract, burn fuel and pump out a wide variety of proteins and other substances.

The N.I.H. researchers suspected that some of those substances migrated from the muscles into the bloodstream and then to the brain, where they most likely contributed to brain health.

But which substances were involved was largely a mystery.

So for the new study, which was published last month in Cell Metabolism, the N.I.H. researchers first isolated muscle cells from mice in petri dishes and doused them with a peptide that affects cell metabolism in ways that mimic aerobic exercise. In effect, they made the cells think that they were running.

Then, using a technique called mass spectrometry, the scientists analyzed the many chemicals that the muscle cells released after their pseudo-workouts, focusing on those few that can cross the blood-brain barrier.

They zeroed in on one substance in particular, a protein called cathepsin B. The protein is known to help sore muscles recover, in part by helping to clear away cellular debris, but it had not previously been considered part of the chain linking exercise to brain health.

To determine whether cathepsin B might, in fact, be involved in brain health, the researchers added a little of the protein to living neurons in other petri dishes. They found that those brain cells started making more proteins related to neurogenesis.

Cathepsin B also proved to be abundant in the bloodstreams of mice, monkeys and people who took up running, the scientists found. In experiments undertaken in collaboration with colleagues in Germany, the researchers had mice run for several weeks, while rhesus monkeys and young men and women took to treadmills for four months, exercising vigorously about three times a week for approximately an hour or sometimes longer.

During that time, the concentrations of cathepsin B in the jogging animals and people steadily rose, the researchers found, and all of the runners began to perform better on various tests of memory and thinking.

Most striking, in the human volunteers, the men and women whose fitness had increased the most — suggesting that they had run particularly intensely — not only had the highest levels of cathepsin B in their blood but also the most-improved test scores.

Finally, because there’s nothing like removing something from the body to underscore how important it may be, the scientists bred mice without the ability to create cathepsin B, including after exercise. The researchers had those mice and other, normal animals run for a week, then taxed their ability to learn and retain information.

After running, the normal mice learned more rapidly than they had before and also held on to those new memories well. But the animals that could not produce cathepsin B learned haltingly and soon forgot their new skills. Running had not helped them to become smarter.

The lesson of these experiments is that our brains appear to function better when they are awash in cathepsin B and we make more cathepsin B when we exercise, says Henriette van Praag, an investigator at the National Institute on Aging at the N.I.H. who oversaw this study.

Of course, increases in cathepsin B explain only part of the benefits of exercise for the brain, she said. She and her colleagues plan to continue looking for other mechanisms in future studies.

They also hope to learn more about how much exercise is necessary to gain brain benefits. The regimen that the human runners followed in this study was “fairly intensive,” she said, but it’s possible that lighter workouts would be almost as effective.

“There is good reason to think,” she said, “that any amount of exercise is going to be better than none” for brain health.

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With Hippotherapy, the Horse Provides the Therapy

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Credit Whitten Sabbatini for The New York Times NYTCREDIT: Whitten Sabbatini for The New York Times

Three-year-old Jack Foster sat on his mother’s lap as she wrapped a towel carefully around his neck.

“Jack has cerebral palsy and low muscle tone,” said his mother, Emily Foster, of Northbrook, Ill. “The biggest challenge is holding his head up.”

With help from his occupational therapist, Ms. Foster fit a riding helmet on Jack’s head and clicked the chinstrap buckle into place. She then watched as the occupational therapist and two volunteers positioned her young son onto a red pony. Jack seemed delighted as one volunteer stood to his right and softly sang, while another led the pony slowly around the arena.

Jack was at Horsefeathers Therapeutic Riding in Lake Forest, Ill., for hippotherapy, a form of equine-assisted therapy conducted by licensed physical, occupational and speech therapists to improve muscle tone, speech and other functions (“hippos” is the Greek word for horse; the American Hippotherapy Association has a therapist locator at americanhippotherapyassociation.org). Hippotherapy is used to treat a variety of conditions, including brain injuries, cerebral palsy, spine curvature, intellectual disabilities, language disorders and sensory processing disorders.

The natural movements of the horse and the environmental cues enable therapists to work toward treatment goals in a setting that might feel like fun, but that research shows can have real benefits. A recent study in Physical & Occupational Therapy in Pediatrics, for example, found that children with cerebral palsy had increased body control after only 10 sessions of hippotherapy. Gross and fine motor skills also improved.

A horse striding around the barn takes around 100 steps a minute, said Dr. Tim Shurtleff, an instructor with the occupational therapy program at Washington University in St. Louis. Each stride pushes the rider’s pelvis forward, so after 35 minutes, a rider undergoes more than 3,000 repetitions of “trunk challenge,” in which the trunk is pushed forward and back. With each step the horse takes, the rider must subtly work to stay upright.

“That’s the power of this – it’s an intensive movement experience,” Dr. Shurtleff said. “The person on the horse is forced to respond to that movement.”

For riders like Jack Foster, who has been doing hippotherapy for over a year, the pelvic thrust helps to strengthen the low muscle tone in his neck and trunk, while relaxing the muscles in his hips and thighs. In his daily life “he will arch and extend, which makes his hips and his thighs really tight,” Ms. Foster said. “Sitting on the horse stretches it.”

During a typical therapy session, Jack sits on this horse facing both forward and backwards. Sessions can include a ball toss or placing rings onto long rods and cones, designed to improve trunk and neck control as well as his reaching abilities.

Researchers are now testing hippotherapy as an intervention for adults with multiple sclerosis and other neurological disorders. Dr. Deborah Silkwood-Sherer, the program director for the physical therapy department at Central Michigan University, said hippotherapy can also boost motivation in children who have disabilities and have been in therapy for years.

“People don’t realize they are working hard on a horse,” Dr. Silkwood-Sherer said. The visual and sensory input of a barn and stable setting provides additional stimulation. “For kids, they never think they are doing therapy.”

Meredith Bazaar of Ringwood, N.J., a speech and language pathologist, uses hippotherapy to treat clients, including those with apraxia, a brain disorder that makes it difficult to articulate or speak words.

“The movement of the horse is so repetitive and coordinated,” she said, allowing her to manipulate a client’s lips, chin or cheeks with her hands to help them make a desired sound. With every stride the horse takes, the client repeats the target sound, such as “ga,” which might double as a command to have the horse “go.”

At Horsefeathers, the founder and executive officer Nick Coyne has 10 gentle horses and ponies he uses for both hippotherapy and adaptive riding, which enables people with physical and mental disabilities to ride horses. He refers to some of his animals as “bomb horses,” meaning a bomb could go off and the horse would not react.

The horses are all trained to stop promptly if they sense a rider is slipping and to ignore the sudden, delighted shrieks a rider might make, as well as spastic movements, Mr. Coyne said.

Alex Brock, 22 of Lake Bluff, Ill., has microcephaly and cerebral palsy, and is also nonverbal and incontinent and has difficulty processing language. He aged out of the public school system, but once a week he eagerly leaves his wheelchair to work with Mr. Coyne as an adaptive rider.

His mother, Trina Brock, was initially incredulous when she heard about adaptive riding at Alex’s former high school. “My first thought was, how is he going to ride a horse?” she said. But she said her son now eagerly anticipates his weekly visits to the barn, and says the exercise helps strengthen his trunk.

It takes three people to help Alex ride, and Ms. Brock said the first time she saw her son on a horse, “I cried.”

Hippotherapy is not suitable for everyone. Ms. Bazaar said some clients turn out to have horse allergies, and allergy medications can make them too drowsy to participate. People with spinal abnormalities like spina bifida may not be good candidates either, and those with Down syndrome and other conditions should be first examined by a physician to determine if their spines are stable enough to endure the rides, she said.

But for children like Jack Foster, riding a horse can open up new opportunities. “It was the first therapy he had done without me,” his mother said.

How Exercise May Help the Brain Grow Stronger

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Credit Getty Images

Physical activity is good for our brains. A wealth of science supports that idea. But precisely how exercise alters and improves the brain remains somewhat mysterious.

A new study with mice fills in one piece of that puzzle. It shows that, in rodents at least, strenuous exercise seems to beneficially change how certain genes work inside the brain. Though the study was in mice, and not people, there are encouraging hints that similar things may be going on inside our own skulls.

For years, scientists have known that the brains of animals and people who regularly exercise are different than the brains of those who are sedentary. Experiments in animals show that, for instance, exercise induces the creation of many new cells in the hippocampus, which is a part of the brain essential for memory and learning, and also improves the survival of those fragile, newborn neurons.

Researchers believe that exercise performs these feats at least in part by goosing the body’s production of a substance called brain-derived neurotropic factor, or B.D.N.F., which is a protein that scientists sometimes refer to as “Miracle-Gro” for the brain. B.D.N.F. helps neurons to grow and remain vigorous and also strengthens the synapses that connect neurons, allowing the brain to function better. Low levels of B.D.N.F. have been associated with cognitive decline in both people and animals. Exercise increases levels of B.D.N.F. in brain tissue.

But scientists have not understood just what it is about exercise that prompts the brain to start pumping out additional B.D.N.F.

So for the new study, which was published this month in the journal eLIFE, researchers with New York University’s Langone Medical Center and other institutions decided to microscopically examine and reverse engineer the steps that lead to a surge in B.D.N.F. after exercise.

They began by gathering healthy mice. Half of the animals were put into cages that contained running wheels. The others were housed without wheels. For a month, all of the animals were allowed to get on with their lives. Those living with wheels ran often, generally covering several miles a day, since mice like to run. The others remained sedentary.

After four weeks, the scientists looked at brain tissue from the hippocampus of both groups of animals, checking for B.D.N.F. levels. As expected, the levels were much higher in the brains of the runners.

But then, to better understand why the runners had more B.D.N.F., the researchers turned to the particular gene in the animals’ DNA that is known to create B.D.N.F. For some reason, the scientists realized, this gene was more active among the animals that exercised than those that did not.

Using sophisticated testing methods, the scientists soon learned why. In both groups of animals, the B.D.N.F. gene was partially covered with clusters of a particular type of molecule that binds to the gene, though in different amounts.

In the sedentary mice, these molecules swarmed so densely over the gene that they blocked signals that tell the gene to turn on. As a result, the B.D.N.F. genes of the sedentary animals were relatively muted, pumping out little B.D.N.F.

But among the runners, the molecular blockade was much less effective. The molecules couldn’t seem to cover and bind to the entire B.D.N.F. gene. So messages from the body continued to reach the gene and tell it to turn on and produce more B.D.N.F.

Perhaps most remarkably, the researchers also found a particular substance in the runners’ brains that fended off the action of these obstructionist molecules. The runners’ brains contained high levels of ketones, which are a byproduct of the breakdown of fat. During strenuous exercise, the body relies in part on fat for fuel and winds up creating ketones, some of which migrate to the brain. (They are tiny enough to cross the blood-brain barrier.) The brain uses these ketones for fuel when blood sugar levels grow low.

But it appears that ketones also cause the molecules that hinder the B.D.N.F. gene to loosen their grip, as the scientists realized when they experimentally added ketones to brain tissue from some of the mice. Afterward, their B.D.N.F. genes were not blocked by nearly as many of the bothersome molecules, and those genes could get on with the job of making B.D.N.F.

None of this occurred in the brains of the sedentary mice.

“It’s incredible just how pervasive and complex the effects of exercise are on the brain,” said Moses Chao, a professor at the Skirball Institute of Biomolecular Medicine at N.Y.U. who oversaw the study.

Whether the same mechanisms that occur in mice occur in our own brains when we exercise is still unknown. But, Dr. Chao pointed out, like the mice, we have more B.D.N.F. in our bodies after exercise. We also create ketones when we exercise, and those ketones are known to migrate to our brains..

Generally, however, this process requires exerting yourself vigorously for an hour or more, after which time your body, having exhausted its stores of sugar, starts burning stored fat and making ketones.

If an hour or more of intense exercise seems daunting — and it does to me — don’t despair. “We are only starting to understand” the many ways in which exercise of any kind and amount is likely to alter our brains, Dr. Chao said. For now, he says, “it’s a very good idea to just keep moving.”

Yoga May Be Good for the Brain

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A weekly routine of yoga and meditation may strengthen thinking skills and help to stave off aging-related mental decline, according to a new study of older adults with early signs of memory problems.

Most of us past the age of 40 are aware that our minds and, in particular, memories begin to sputter as the years pass. Familiar names and words no longer spring readily to mind, and car keys acquire the power to teleport into jacket pockets where we could not possibly have left them.

Some weakening in mental function appears to be inevitable as we age. But emerging science suggests that we might be able to slow and mitigate the decline by how we live and, in particular, whether and how we move our bodies. Past studies have found that people who run, weight train, dance, practice tai chi, or regularly garden have a lower risk of developing dementia than people who are not physically active at all.

There also is growing evidence that combining physical activity with meditation might intensify the benefits of both pursuits. In an interesting study that I wrote about recently, for example, people with depression who meditated before they went for a run showed greater improvements in their mood than people who did either of those activities alone.

But many people do not have the physical capacity or taste for running or other similarly vigorous activities.

So for the new study, which was published in April in the Journal of Alzheimer’s Disease, researchers at the University of California, Los Angeles, and other institutions decided to test whether yoga, a relatively mild, meditative activity, could alter people’s brains and fortify their ability to think.

They began by recruiting 29 middle-aged and older adults from the Los Angeles area who told the researchers that they were anxious about the state of their memories and who, during evaluations at the university, were found to have mild cognitive impairment, a mental condition that can be a precursor to eventual dementia.

The volunteers also underwent a sophisticated type of brain scan that tracks how different parts of the brain communicate with one another.

The volunteers then were divided into two groups. One began a well-established brain-training program that involves an hour a week of classroom time and a series of mental exercises designed to bolster their memory that volunteers were asked to practice at home for about 15 minutes a day.

The others took up yoga. For an hour each week, they visited the U.C.L.A. campus to learn Kundalini yoga, which involves breathing exercises and meditation as well as movement and poses. The researchers chose this form of yoga largely because people who are out of shape or new to yoga generally find it easy to complete the classes.

The yoga group also was taught a type of meditation known as Kirtan Kriya that involves repeating a series of sounds — a mantra — while simultaneously “dancing” with repetitive hand movements. They were asked to meditate in this way for 15 minutes every day, so that the total time commitment was equivalent for both groups.

The volunteers practiced their programs for 12 weeks.

Then they returned to the university’s lab for another round of cognitive tests and a second brain scan.

By this time, all of the men and women were able to perform significantly better on most tests of their thinking.

But only those who had practiced yoga and meditation showed improvements in their moods — they scored lower on an assessment of potential depression than those in the brain-training group — and they performed much better on a test of visuospatial memory, a type of remembering that is important for balance, depth perception and the ability to recognize objects and navigate the world.

The brain scans in both groups displayed more communication now between parts of their brains involved in memory and language skills. Those who had practiced yoga, however, also had developed more communication between parts of the brain that control attention, suggesting a greater ability now to focus and multitask.

In effect, yoga and meditation had equaled and then topped the benefits of 12 weeks of brain training.

“We were a bit surprised by the magnitude” of the brain effects, said Dr. Helen Lavretsky, a professor of psychiatry at U.C.L.A. who oversaw the study.

How, physiologically, yoga and meditation had uniquely changed the volunteers’ brains is impossible to know from this study, although reductions in stress hormones and anxiety are likely to play a substantial role, she said. “These were all people worried about the state of their minds,” she pointed out.

Movement also increases the levels of various biochemicals in the muscles and brains that are associated with improved brain health, she said.

Whether other forms of yoga and meditation or either activity on its own might likewise bulk up the brain remains a mystery, she said. But there may be something especially potent, she said, about combining yoga with the type of meditation practiced in this study, during which people were not completely still.

The Alzheimer’s Research and Prevention Foundation, which partially funded this study, provides information on its website about how to start meditating in this style, if you would like to try.

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Walk, Jog or Dance: It’s All Good for the Aging Brain

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Credit Illustration by Sam Island

More people are living longer these days, but the good news comes shadowed by the possible increase in cases of age-related mental decline. By some estimates, the global incidence of dementia will more than triple in the next 35 years. That grim prospect is what makes a study published in March in The Journal of Alzheimer’s Disease so encouraging: It turns out that regular walking, cycling, swimming, dancing and even gardening may substantially reduce the risk of Alzheimer’s.

Exercise has long been linked to better mental capacity in older people. Little research, however, has tracked individuals over years, while also including actual brain scans. So for the new study, researchers at the University of California, Los Angeles, and other institutions analyzed data produced by the Cardiovascular Health Study, begun in 1989, which has evaluated almost 6,000 older men and women. The subjects complete medical and cognitive tests, fill out questionnaires about their lives and physical activities and receive M.R.I. scans of their brains. Looking at 10 years of data from nearly 900 participants who were at least 65 upon entering the study, the researchers first determined who was cognitively impaired, based on their cognitive assessments. Next they estimated the number of calories burned through weekly exercise, based on the participants’ questionnaires.

The scans showed that the top quartile of active individuals proved to have substantially more gray matter, compared with their peers, in those parts of the brain related to memory and higher-­level thinking. More gray matter, which consists mostly of neurons, is generally equated with greater brain health. At the same time, those whose physical activity increased over a five-year period — though these cases were few — showed notable increases in gray-matter volume in those same parts of their brains. And, perhaps most meaningful, people who had more gray matter correlated with physical activity also had 50 percent less risk five years laterof having experienced memory decline or of having developed Alzheimer’s.

“For the purposes of brain health, it looks like it’s a very good idea to stay as physically active as possible,” says Cyrus Raji, a senior radiology resident at U.C.L.A., who led the study. He points out that “physical activity” is an elastic term in this study: It includes walking, jogging and moderate cycling as well as gardening, ballroom dancing and other calorie-burning recreational pursuits. Dr. Raji said he hopes that further research might show whether this caloric expenditure is remodeling the brain, perhaps by reducing inflammation or vascular diseases.

The ideal amount and type of activity for staving off memory loss is unknown, he says, although even the most avid exercisers in this group were generally cycling or dancing only a few times a week. Still, the takeaway is that physical activity might change aging’s arc. “If we want to live a long time but also keep our memories, our basic selves, intact, keep moving,” Dr. Raji says.

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Meditation Plus Running as a Treatment for Depression

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Meditating before running could change the brain in ways that are more beneficial for mental health than practicing either of those activities alone, according to an interesting study of a new treatment program for people with depression.

As many people know from experience, depression is characterized in part by an inability to stop dwelling on gloomy thoughts and unhappy memories from the past. Researchers suspect that this thinking pattern, known as rumination, may involve two areas of the brain in particular: the prefrontal cortex, a part of the brain that helps to control attention and focus, and the hippocampus, which is critical for learning and memory. In some studies, people with severe depression have been found to have a smaller hippocampus than people who are not depressed.

Interestingly, meditation and exercise affect those same portions of the brain, although in varying ways. In brain-scan studies, people who are long-term meditators, for instance, generally display different patterns of brain-cell communication in their prefrontal cortex during cognitive tests than people who don’t meditate. Those differences are believed to indicate that the meditators possess a more honed ability to focus and concentrate.

Meanwhile, according to animal studies, aerobic exercise substantially increases the production of new brain cells in the hippocampus.

Both meditation and exercise also have proven beneficial in the treatment of anxiety, depression and other mood disorders.

These various findings about exercise and meditation intrigued researchers at Rutgers University in New Brunswick, N.J., who began to wonder whether, since meditation and exercise on their own improve moods, combining the two might intensify the impacts of each.

So, for the new study, which was published last month in Translational Psychiatry, the scientists recruited 52 men and women, 22 of whom had been given diagnoses of depression. The researchers confirmed that diagnosis with their own tests and then asked all of the volunteers to complete a computerized test of their ability to focus while sensors measured electrical signals in their brains.

The researchers found that the depressed volunteers showed signaling patterns in their prefrontal cortex that are associated with poor concentration and focus.

Then the researchers had all of the volunteers begin a fairly rigorous, supervised program of sitting, followed by sweating.

To start, the volunteers were taught a form of meditation known as focused attention. Essentially entry-level mindfulness meditation, it requires people to sit quietly and think about their respiration by counting their breaths up to 10 and then backward. This practice is not easy, especially at first.

“If people found their thoughts wandering” during the meditation, and especially if they began to ruminate on unpleasant memories, they were told not to worry or judge themselves, “but just to start counting again from one,” said Brandon Alderman, a professor of exercise science at Rutgers who led the study.

The volunteers meditated in this way for 20 minutes, then stood and undertook 10 minutes of walking meditation, in which they paid close attention to each footfall.

Then they clambered onto treadmills or stationary bicycles at the lab and jogged or pedaled at a moderate pace for 30 minutes (with five minutes of warming up and five minutes of cooling down).

The volunteers completed these sessions twice a week for eight weeks. Then the researchers retested their moods and their ability to focus and concentrate.

There were significant changes. The 22 volunteers with depression now had a 40 percent reduction in symptoms of the condition. They reported, in particular, much less inclination to ruminate over bad memories.

Meanwhile, the members of the healthy control group also reported feeling happier than they had at the start of the study.

Objectively, the volunteers’ results on the computerized tests of their ability to focus and their brain activity also were different. The group with depression now showed brain cell activity in their prefrontal cortex that was almost identical to that of the people without depression. They could concentrate much better and hone their attention, attributes that are believed to help reduce stubborn rumination.

“I was quite surprised that we saw such a robust effect after only eight weeks,” Dr. Alderman said.

He and his colleagues theorize that the meditation and exercise may have produced synergistic effects on the brains of their volunteers.

“We know from animal studies that effortful learning, such as is involved in learning how to meditate, encourages new neurons to mature” in the hippocampus, he said.

So while the exercise most likely increased the number of new brain cells in each volunteer’s hippocampus, Dr. Alderman said, the meditation may have helped to keep more of those neurons alive and functioning than if people had not meditated.

Meditation also may have made the exercise more tolerable, he said, since some studies indicate that being mindful of your breathing and your body during workouts increases people’s enjoyment of the exertion.

“I’ve started meditating,” said Dr. Alderman, a long-time athlete.

Of course, this was a small study and the scientists did not follow their volunteers long term, so they do not know if any mood improvements linger. They also have no idea whether similar or even greater benefits might occur if someone were to run and then meditate or to practice both activities but on alternating days. They plan to study those questions in future experiments.

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Learning a New Sport May Be Good for the Brain

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Gretchen Reynolds, Phys Ed columnist, tries snowboarding for the first time.

Gretchen Reynolds, Phys Ed columnist, tries snowboarding for the first time.Credit Lynn Tran

Learning in midlife to juggle, swim, ride a bicycle or, in my case, snowboard could change and strengthen the brain in ways that practicing other familiar pursuits such as crossword puzzles or marathon training will not, according to an accumulating body of research about the unique impacts of motor learning on the brain.

When most of us consider learning and intelligence, we think of activities such as adding numbers, remembering names, writing poetry, learning a new language.

Such complex thinking generally is classified as “higher-order” cognition and results in activity within certain portions of the brain and promotes plasticity, or physical changes, in those areas. There is strong evidence that learning a second language as an adult, for instance, results in increased white matter in the parts of the brain known to be involved in language processing.

Regular exercise likewise changes the brain, as I frequently have written, with studies in animals showing that running and other types of physical activities increase the number of new brain cells created in parts of the brain that are integral to memory and thinking.

But the impacts of learning on one of the most primal portions of the brain have been surprisingly underappreciated, both scientifically and outside the lab. Most of us pay little attention to our motor cortex, which controls how well we can move.

“We have a tendency to admire motor skills,” said Dr. John Krakauer, a professor of neurology and director of the Center for the Study of Motor Learning and Brain Repair at Johns Hopkins University in Baltimore. We like watching athletes in action, he said. But most of us make little effort to hone our motor skills in adulthood, and very few of us try to expand them by, for instance, learning a new sport.

We could be short-changing our brains.

Past neurological studies in people have shown that learning a new physical skill in adulthood, such as juggling, leads to increases in the volume of gray matter in parts of the brain related to movement control.

Even more compelling, a 2014 study with mice found that when the mice were introduced to a complicated type of running wheel, in which the rungs were irregularly spaced so that the animals had to learn a new, stutter-step type of running, their brains changed significantly. Learning to use these new wheels led to increased myelination of neurons in the animals’ motor cortexes. Myelination is the process by which parts of a brain cell are insulated, so that the messages between neurons can proceed more quickly and smoothly.

Scientists once believed that myelination in the brain occurs almost exclusively during infancy and childhood and then slows or halts altogether.

But the animals running on the oddball wheels showed notable increases in the myelination of the neurons in their motor cortex even though they were adults.

At the same time, other animals that simply ran on normal wheels for the same period of time showed no increase in myelination afterward.

In other words, learning the new skill had changed the inner workings of the adult animals’ motor cortexes; practicing a well-mastered one had not.

“We don’t know” whether comparable changes occur within the brains of grown people who take up a new sport or physical skill, Dr. Krakauer said. But it seems likely, he said. “Motor skills are as cognitively challenging” in their way as traditional brainteasers such as crossword puzzles or brain-training games, he said. So adding a new sport to your repertory should have salutary effects on your brain, and also, unlike computer-based games, provide all the physical benefits of exercise.

These considerations cheered me a few weeks ago when I took to the slopes of my local mountain for a weekend-long crash course in snowboarding. (Crashing, regrettably, is inevitable while learning to shred.) I had wondered if I might be too advanced in years and hardened in the habits of skiing to learn to ride. But the experience was in fact exhilarating and glorious. Learning a new sport or skill when you are old enough to be a parent to your instructor is psychologically uplifting, as well as beneficial for the body and brain. It reminds you that your body can still respond, that it can still yearn for movement and speed.

By the end of the second day, I attempted my first moguls on a snowboard and completed precisely one turn before auguring hindside into the slope and slipping and picking my way down the rest of the run. But one mogul turn was 100 percent more than I had managed before. I now aim to return to the mountain and double that number to two turns, which is how we learn and progress and, with luck, change our minds — both literally and about our limits.

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Which Type of Exercise Is Best for the Brain?

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Some forms of exercise may be much more effective than others at bulking up the brain, according to a remarkable new study in rats. For the first time, scientists compared head-to-head the neurological impacts of different types of exercise: running, weight training and high-intensity interval training. The surprising results suggest that going hard may not be the best option for long-term brain health.

As I have often written, exercise changes the structure and function of the brain. Studies in animals and people have shown that physical activity generally increases brain volume and can reduce the number and size of age-related holes in the brain’s white and gray matter.

Exercise also, and perhaps most resonantly, augments adult neurogenesis, which is the creation of new brain cells in an already mature brain. In studies with animals, exercise, in the form of running wheels or treadmills, has been found to double or even triple the number of new neurons that appear afterward in the animals’ hippocampus, a key area of the brain for learning and memory, compared to the brains of animals that remain sedentary. Scientists believe that exercise has similar impacts on the human hippocampus.

These past studies of exercise and neurogenesis understandably have focused on distance running. Lab rodents know how to run. But whether other forms of exercise likewise prompt increases in neurogenesis has been unknown and is an issue of increasing interest, given the growing popularity of workouts such as weight training and high-intensity intervals.

So for the new study, which was published this month in the Journal of Physiology, researchers at the University of Jyvaskyla in Finland and other institutions gathered a large group of adult male rats. The researchers injected the rats with a substance that marks new brain cells and then set groups of them to an array of different workouts, with one group remaining sedentary to serve as controls.

Some of the animals were given running wheels in their cages, allowing them to run at will. Most jogged moderately every day for several miles, although individual mileage varied.

Others began resistance training, which for rats involves climbing a wall with tiny weights attached to their tails.

Still others took up the rodent equivalent of high-intensity interval training. For this regimen, the animals were placed on little treadmills and required to sprint at a very rapid and strenuous pace for three minutes, followed by two minutes of slow skittering, with the entire sequence repeated twice more, for a total of 15 minutes of running.

These routines continued for seven weeks, after which the researchers microscopically examined brain tissue from the hippocampus of each animal.

They found very different levels of neurogenesis, depending on how each animal had exercised.

Those rats that had jogged on wheels showed robust levels of neurogenesis. Their hippocampal tissue teemed with new neurons, far more than in the brains of the sedentary animals. The greater the distance that a runner had covered during the experiment, the more new cells its brain now contained.

There were far fewer new neurons in the brains of the animals that had completed high-intensity interval training. They showed somewhat higher amounts than in the sedentary animals but far less than in the distance runners.

And the weight-training rats, although they were much stronger at the end of the experiment than they had been at the start, showed no discernible augmentation of neurogenesis. Their hippocampal tissue looked just like that of the animals that had not exercised at all.

Obviously, rats are not people. But the implications of these findings are provocative. They suggest, said Miriam Nokia, a research fellow at the University of Jyvaskyla who led the study, that “sustained aerobic exercise might be most beneficial for brain health also in humans.”

Just why distance running was so much more potent at promoting neurogenesis than the other workouts is not clear, although Dr. Nokia and her colleagues speculate that distance running stimulates the release of a particular substance in the brain known as brain-derived neurotrophic factor that is known to regulate neurogenesis. The more miles an animal runs, the more B.D.N.F. it produces.

Weight training, on the other hand, while extremely beneficial for muscular health, has previously been shown to have little effect on the body’s levels of B.D.N.F., Dr. Nokia said, which could explain why it did not contribute to increased neurogenesis in this study.

As for high-intensity interval training, its potential brain benefits may be undercut by its very intensity, Dr. Nokia said. It is, by intent, much more physiologically draining and stressful than moderate running, and “stress tends to decrease adult hippocampal neurogenesis,” she said.

These results do not mean, however, that only running and similar moderate endurance workouts strengthen the brain, Dr. Nokia said. Those activities do seem to prompt the most neurogenesis in the hippocampus. But weight training and high-intensity intervals probably lead to different types of changes elsewhere in the brain. They might, for instance, encourage the creation of additional blood vessels or new connections between brain cells or between different parts of the brain.

So if you currently weight train or exclusively work out with intense intervals, continue. But perhaps also thread in an occasional run or bike ride for the sake of your hippocampal health.

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