brain aging

Does your health in middle age predict how healthy you'll be later in life?

May 28, 2019

Science Daily/American Geriatrics Society

In a new study, researchers identified factors associated with brain health in middle age in order to identify ways to preserve brain function when people are older.

 

Cognitive decline is the medical term for a decline in your abilities to think, remember, and make decisions. Researchers know now that cognitive decline may begin in midlife and can develop over a period of 20 years or so. In a new study, published in the Journal of the American Geriatrics Society (JAGS), researchers identified factors associated with brain health in middle age in order to identify ways to preserve brain function when people are older.

 

Several studies have shown links between changes in the senses and the development of cognitive decline. In earlier studies, the research team responsible for the new JAGS report found that problems with hearing, vision, or the sense of smell were associated with poorer cognitive function in middle-aged adults. These changes also have been linked to developing cognitive impairments for older people.

 

To learn more in this new work, the researchers used information from the ongoing Beaver Dam Offspring Study (BOSS; conducted from 2005 to the present), a study of the adult children of participants in the Epidemiology of Hearing Loss Study, a population-based study of aging.

 

Hearing, vision, and the ability to smell were measured with highly sensitive tests. The participants also took tests to measure their attention, thinking, and decision-making abilities, as well as their memory and ability to communicate. The researchers then combined the results of all these tests to use as a measure of the participants' brain function. Blood tests and other measurements were also taken to create a complete health picture for each participant.

 

There were 2,285 participants included in this study, and most were younger than 65 years of age. Although those participants with signs of brain aging had overall worse performance on the sensory and cognitive tests, their losses in function were mild on average.

 

The researchers reported that participants who smoked, had larger waists, or had health issues related to inflammation or cardiovascular disease were more likely to show signs of brain aging. Older participants and those with diabetes were also more likely to develop brain aging over the following five years. Participants who exercised regularly or had more years of education were less likely to show signs of brain aging.

 

The researchers said their findings add to evidence that issues like diabetes, as well as other related health concerns impacting circulation, inflammation, and metabolism (the medical term for the chemical reactions in our bodies that help sustain life, such as converting food into energy), are important contributors to brain aging.

 

The researchers also noted that even minor injuries to the brain can have long-term effects on brain function. Participants with a history of a head injury had a 77 percent increased risk of developing brain aging. Symptoms of depression were also associated with an increased risk of brain aging.

 

The researchers said their findings suggest that some brain aging may be delayed or prevented. Just as middle-aged people can take steps to prevent heart disease by maintaining a healthy diet and weight and keeping physically active, they can also take steps to prevent early changes in brain health.

 

"Healthy lifestyles are important for healthy aging, and making healthy choices earlier in life may improve health later in life," said lead author Carla R. Schubert, MS. The researchers concluded that identifying and targeting risk factors associated with poor brain function when people are middle-aged could help prevent cognitive decline with age.

https://www.sciencedaily.com/releases/2019/05/190528095240.htm

Brains evolved to need exercise

June 26, 2017

Science Daily/University of Arizona

Mounting scientific evidence shows that exercise is good not only for our bodies, but for our brains. Yet, exactly why physical activity benefits the brain is not well understood. Researchers suggest that the link between exercise and the brain is a product of our evolutionary history and our past as hunter-gatherers.

 

In a new article published in the journal Trends in Neurosciences, University of Arizona researchers suggest that the link between exercise and the brain is a product of our evolutionary history and our past as hunter-gatherers.

 

UA anthropologist David Raichlen and UA psychologist Gene Alexander, who together run a research program on exercise and the brain, propose an "adaptive capacity model" for understanding, from an evolutionary neuroscience perspective, how physical activity impacts brain structure and function.

 

Their argument: As humans transitioned from a relatively sedentary apelike existence to a more physically demanding hunter-gatherer lifestyle, starting around 2 million years ago, we began to engage in complex foraging tasks that were simultaneously physically and mentally demanding, and that may explain how physical activity and the brain came to be so connected.

 

"We think our physiology evolved to respond to those increases in physical activity levels, and those physiological adaptations go from your bones and your muscles, apparently all the way to your brain," said Raichlen, an associate professor in the UA School of Anthropology in the College of Social and Behavioral Sciences.

 

"It's very odd to think that moving your body should affect your brain in this way -- that exercise should have some beneficial impact on brain structure and function -- but if you start thinking about it from an evolutionary perspective, you can start to piece together why that system would adaptively respond to exercise challenges and stresses," he said.

 

Having this underlying understanding of the exercise-brain connection could help researchers come up with ways to enhance the benefits of exercise even further, and to develop effective interventions for age-related cognitive decline or even neurodegenerative diseases such as Alzheimer's.

 

Notably, the parts of the brain most taxed during a complex activity such as foraging -- areas that play a key role in memory and executive functions such as problem solving and planning -- are the same areas that seem to benefit from exercise in studies.

 

"Foraging is an incredibly complex cognitive behavior," Raichlen said. "You're moving on a landscape, you're using memory not only to know where to go but also to navigate your way back, you're paying attention to your surroundings. You're multitasking the entire time because you're making decisions while you're paying attention to the environment, while you are also monitoring your motor systems over complex terrain. Putting all that together creates a very complex multitasking effort."

 

The adaptive capacity model could help explain research findings such as those published by Raichlen and Alexander last year showing that runners' brains appear to be more connected than brains of non-runners.

 

The model also could help inform interventions for the cognitive decline that often accompanies aging -- in a period in life when physical activity levels tend to decline as well.

 

"What we're proposing is, if you're not sufficiently engaged in this kind of cognitively challenging aerobic activity, then this may be responsible for what we often see as healthy brain aging, where people start to show some diminished cognitive abilities," said Alexander, a UA professor of psychology, psychiatry, neuroscience and physiological sciences. "So the natural aging process might really be part of a reduced capacity in response to not being engaged enough."

 

Reduced capacity refers to what can happen in organ systems throughout the body when they are deprived of exercise.

 

"Our organ systems adapt to the stresses they undergo," said Raichlen, an avid runner and expert on running. "For example, if you engage in exercise, your cardiovascular system has to adapt to expand capacity, be it through enlarging your heart or increasing your vasculature, and that takes energy. So if you're not challenging it in that way -- if you're not engaging in aerobic exercise -- to save energy, your body simply reduces that capacity."

 

In the case of the brain, if it is not being stressed enough it may begin to atrophy. This may be especially concerning, considering how much more sedentary humans' lifestyles have become.

 

"Our evolutionary history suggests that we are, fundamentally, cognitively engaged endurance athletes, and that if we don't remain active we're going to have this loss of capacity in response to that," said Alexander, who studies brain aging and Alzheimer's disease as a member of the UA's Evelyn F. McKnight Brain Institute. "So there really may be a mismatch between our relatively sedentary lifestyles of today and how we evolved."

 

Alexander and Raichlen say future research should look at how different levels of exercise intensity, as well as different types of exercise, or exercise paired specifically with cognitive tasks, affect the brain.

 

For example, exercising in a novel environment that poses a new mental challenge, may prove to be especially beneficial, Raichlen said.

 

"Most of the research in this area puts people in a cognitively impoverished environment. They put people in a lab and have them run on a treadmill or exercise bike, and you don't really have to do as much, so it's possible that we're missing something by not increasing novelty," he said.

 

Alexander and Raichlen say they hope the adaptive capacity model will help advance research on exercise and the brain.

 

"This evolutionary neuroscience perspective is something that's been generally lacking in the field," Alexander said. "And we think this might be helpful to advance research and help develop some new specific hypotheses and ways to identify more universally effective interventions that could be helpful to everyone."

https://www.sciencedaily.com/releases/2017/06/170626155729.htm

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