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Exercise is good for the aging brain

Researchers find a single bout of exercise boosts cognition, memory performance in some older people

August 26, 2019

Science Daily/University of Iowa

Researchers have found that a single bout of exercise benefits some older people's brains. In experiments in which participants aged 60 to 80 exercised once and multiple times, the researchers found some individuals showed improved cognitive functions and working memory.

 

Exercise seems to endow a wealth of benefits, from the release of happiness-inducing hormones to higher physical fitness. New research shows it may provide a boost to the mind too.

 

University of Iowa researchers have found that a single bout of exercise improves cognitive functions and working memory in some older people. In experiments that included physical activity, brain scans, and working memory tests, the researchers also found that participants experienced the same cognitive benefits and improved memory from a single exercise session as they did from longer, regular exercise.

 

"One implication of this study is you could think of the benefits day by day," says Michelle Voss, assistant professor in the Department of Psychological and Brain Sciences and the study's corresponding author. "In terms of behavioral change and cognitive benefits from physical activity, you can say, 'I'm just going to be active today. I'll get a benefit.' So, you don't need to think of it like you're going to train for a marathon to get some sort of optimal peak of performance. You just could work at it day by day to gain those benefits."

 

Previous research has shown exercise can confer a mental boost. But the benefits vary: One person may improve cognitively and have improved memory, while another person may show little to no gain.

 

Limited research has been done on how a single bout of physical activity may affect cognition and working memory specifically in older populations, despite evidence that some brain functions slip as people age.

 

Voss wanted to tease out how a single session of exercise may affect older individuals. Her team enrolled 34 adults between 60 and 80 years of age who were healthy but not regularly active. Each participant rode a stationary bike on two separate occasions -- with light and then more strenuous resistance when pedaling -- for 20 minutes. Before and after each exercise session, each participant underwent a brain scan and completed a memory test.

 

In the brain scan, the researchers examined bursts of activity in regions known to be involved in the collection and sharing of memories. In the working memory tests, each participant used a computer screen to look at a set of eight young adult faces that rotated every three seconds -- flashcard style -- and had to decide when a face seen two "cards" previously matched the one they were currently viewing.

 

After a single exercise session, the researchers found in some individuals increased connectivity between the medial temporal (which surrounds the brain's memory center, the hippocampus) and the parietal cortex and prefrontal cortex, two regions involved in cognition and memory. Those same individuals also performed better on the memory tests. Other individuals showed little to no gain.

 

The boost in cognition and memory from a single exercise session lasted only a short while for those who showed gains, the researchers found.

 

"The benefits can be there a lot more quickly than people think," Voss says. "The hope is that a lot of people will then keep it up because those benefits to the brain are temporary. Understanding exactly how long the benefits last after a single session, and why some benefit more than others, are exciting directions for future research."

 

The participants also engaged in regular exercise, pedaling on a stationary bike for 50 minutes three times a week for three months. One group engaged in moderate-intensity pedaling, while another group had a mostly lighter workout in which the bike pedals moved for them.

 

Most individuals in the moderate and lighter-intensity groups showed mental benefits, judging by the brain scans and working memory tests given at the beginning and at the end of the three-month exercise period. But the brain gains were no greater than the improvements from when they had exercised a single time.

 

"The result that a single session of aerobic exercise mimics the effects of 12 weeks of training on performance has important implications both practically and theoretically," the authors write.

 

The researchers note their study had a small participant pool, with a homogenous population that excluded anyone with chronic health conditions or who were taking beta-blockers.

 

To address those limitations, Voss has expanded her participant pool in a current, five-year study to confirm the initial findings and learn more about how exercise alters older people's brains. The participants are healthy older individuals who are not physically active, similar to the participants' profile in the study's results reported here.

 

The National Institute on Aging, part of the National Institutes of Health, funded the research.

https://www.sciencedaily.com/releases/2019/08/190826110409.htm

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Impaired brain activity in rats with family history of alcohol abuse

Atypical prefrontal cortex function could be target of alcohol use disorder treatment

July 29, 2019

Science Daily/Society for Neuroscience

Neural activity that reflects the intention to drink alcohol is observed in the prefrontal cortex and is blunted in rats with a family history of excessive drinking, according to research from eNeuro. This insight could lead to novel treatments for alcohol use disorders.

 

The prefrontal cortex is a brain region involved in decision-making that becomes active before a behavior is initiated, indicating intention. David Linsenbardt, Nicholas Timme, and Christopher Lapish at Indiana University Purdue University Indianapolis investigated neural activity in the prefrontal cortex to determine if it encodes the intention to consume alcohol.

 

Linsenbardt's team compared activity before and during alcohol consumption in two types of rats. One modeled a family history of alcohol abuse, while the other lacked this family history. The prefrontal cortex was active during consumption in both types of rats, but only active pre-consumption in the rats without a family history of drinking.

 

These findings suggest that the prefrontal cortex directly encodes the intention to consume alcohol but less so in those with greater risk of abusing alcohol. Restoring prefrontal cortex activity in individuals with a predisposition to over-drink could be a new approach for treating alcohol use disorders.

https://www.sciencedaily.com/releases/2019/07/190729132334.htm

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Brain wave stimulation may improve Alzheimer's symptoms

Noninvasive treatment improves memory and reduces amyloid plaques in mice

March 14, 2019

Science Daily/Massachusetts Institute of Technology

By exposing mice to a unique combination of light and sound, neuroscientists have shown they can improve cognitive and memory impairments similar to those seen in Alzheimer's patients.

 

This noninvasive treatment, which works by inducing brain waves known as gamma oscillations, also greatly reduced the number of amyloid plaques found in the brains of these mice. Plaques were cleared in large swaths of the brain, including areas critical for cognitive functions such as learning and memory.

 

"When we combine visual and auditory stimulation for a week, we see the engagement of the prefrontal cortex and a very dramatic reduction of amyloid," says Li-Huei Tsai, director of MIT's Picower Institute for Learning and Memory and the senior author of the study.

 

Further study will be needed, she says, to determine if this type of treatment will work in human patients. The researchers have already performed some preliminary safety tests of this type of stimulation in healthy human subjects.

 

MIT graduate student Anthony Martorell and Georgia Tech graduate student Abigail Paulson are the lead authors of the study, which appears in the March 14 issue of Cell.

 

Memory improvement

 

The brain's neurons generate electrical signals that synchronize to form brain waves in several different frequency ranges. Previous studies have suggested that Alzheimer's patients have impairments of their gamma-frequency oscillations, which range from 25 to 80 hertz (cycles per second) and are believed to contribute to brain functions such as attention, perception, and memory.

 

In 2016, Tsai and her colleagues first reported the beneficial effects of restoring gamma oscillations in the brains of mice that are genetically predisposed to develop Alzheimer's symptoms. In that study, the researchers used light flickering at 40 hertz, delivered for one hour a day. They found that this treatment reduced levels of beta amyloid plaques and another Alzheimer's-related pathogenic marker, phosphorylated tau protein. The treatment also stimulated the activity of debris-clearing immune cells known as microglia.

 

In that study, the improvements generated by flickering light were limited to the visual cortex. In their new study, the researchers set out to explore whether they could reach other brain regions, such as those needed for learning and memory, using sound stimuli. They found that exposure to one hour of 40-hertz tones per day, for seven days, dramatically reduced the amount of beta amyloid in the auditory cortex (which processes sound) as well as the hippocampus, a key memory site that is located near the auditory cortex.

 

"What we have demonstrated here is that we can use a totally different sensory modality to induce gamma oscillations in the brain. And secondly, this auditory-stimulation-induced gamma can reduce amyloid and Tau pathology in not just the sensory cortex but also in the hippocampus," says Tsai, who is a founding member of MIT's Aging Brain Initiative.

 

The researchers also tested the effect of auditory stimulation on the mice's cognitive abilities. They found that after one week of treatment, the mice performed much better when navigating a maze requiring them to remember key landmarks. They were also better able to recognize objects they had previously encountered.

 

They also found that auditory treatment induced changes in not only microglia, but also the blood vessels, possibly facilitating the clearance of amyloid.

 

Dramatic effect

 

The researchers then decided to try combining the visual and auditory stimulation, and to their surprise, they found that this dual treatment had an even greater effect than either one alone. Amyloid plaques were reduced throughout a much greater portion of the brain, including the prefrontal cortex, where higher cognitive functions take place. The microglia response was also much stronger.

 

"These microglia just pile on top of one another around the plaques," Tsai says. "It's very dramatic."

 

The researchers found that if they treated the mice for one week, then waited another week to perform the tests, many of the positive effects had faded, suggesting that the treatment would need to be given continually to maintain the benefits.

 

In an ongoing study, the researchers are now analyzing how gamma oscillations affect specific brain cell types, in hopes of discovering the molecular mechanisms behind the phenomena they have observed. Tsai says she also hopes to explore why the specific frequency they use, 40 hertz, has such a profound impact.

 

The combined visual and auditory treatment has already been tested in healthy volunteers, to assess its safety, and the researchers are now beginning to enroll patients with early-stage Alzheimer's to study its possible effects on the disease.

 

The research was funded, in part, by the Robert and Renee Belfer Family Foundation, the Halis Family Foundation, the JPB Foundation, the National Institutes of Health and the MIT Aging Brain Initiative. 

https://www.sciencedaily.com/releases/2019/03/190314111004.htm

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