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Exercise improves brain function and possibly reduces dementia risk

A study led by scientists at Rutgers University in New Brunswick has shown that specialized cells involved in how the body responds to insulin are activated in the brain after exercise, suggesting that physical activity can directly improve brain function. .

A study, published in aged cella journal focused on the biology of aging, indicates that therapies targeting this action of insulin can be developed to compensate or even prevent the progression of dementia.

“We think this work is important because it suggests that exercise can improve cognition and memory by improving the ability of insulin to act in the brain,” said Steven Malin, associate professor in the School of Medicine’s Department of Kinesiology and Health. from Rutgers. Arts and Sciences and lead author of the study.

Conducted in collaboration with the National Institute on Aging of the National Institutes of Health, the researchers focused on the role of neuronal extracellular vesicles, specialized cells released by the brain.

Extracellular vesicles, once dismissed by researchers as “cellular dust,” have over the past 15 years grown exponentially in recognition as important players in the microscopic world of the human body, facilitating the transport of key molecules, such as proteins, between cells. cells. For this study, the scientists focused on vesicles produced in the brain that carry several proteins involved in insulin sensitivity, one of which is called Akt.

Insulin sensitivity is a measure of how well the body responds to insulin, a hormone that controls blood sugar levels. People with high insulin sensitivity can use blood glucose more efficiently in the body, such as in muscles, which lowers blood sugar. People with diabetes, with its key symptom of low insulin sensitivity or insulin resistance, have brain cells that are less responsive to insulin. This can have negative impacts on cognition.

The researchers were able to study the vesicles by isolating them from the blood of participants in an experimental study. The trial, conducted over two weeks, included a group of 21 volunteers who had an average age of 60 years and prediabetes. Throughout the study, they performed 12 individual, supervised, 60-minute exercise sessions of moderate to high intensity. Participants drank a glucose drink before and after training. The researchers then collected blood samples before and during the participants’ drinking at the beginning and end of the workout.

Blood samples showed that the number of neuronal vesicles carrying proteins involved in insulin sensitivity increased after each workout, with Akt being the most notable.

“We show for the first time that exercise affects insulin signaling from neuronal extracellular vesicles in relation to clinical improvements in blood sugar,” Malin said. “And we used these neuronal extracellular vesicles as an indicator of the brain’s insulin sensitivity.”

Therefore, exercise is potentially capable of improving the brain’s ability to respond to insulin for neuronal function, he said.

Insulin is a hormone increasingly recognized for regulating cognition, the mental process of acquiring knowledge through thought, experience, and the senses. Prediabetes is a serious health condition that occurs when blood sugar levels are higher than normal, but not high enough to be diagnosed as type 2 diabetes. People with prediabetes are at risk of having insufficient levels. of insulin in their bodies, particularly in the brain, which increases the chances of developing dementia diseases such as Alzheimer’s, Malin said.

Insulin also plays a crucial role in memory formation, recall, processing speed, and the functioning of synapses, structures that allow brain cells to communicate with each other.

“If insulin is insufficient in the brain, that means that not only will brain cells become potentially dysfunctional, but they may also stop interacting with each other properly,” Malin said. “It’s like playing telephone with a friend. At some point the message is lost when the brain becomes resistant to insulin.”

Exercise has long been believed to improve cognition, but the mechanisms involved were unclear. Previous studies have uncovered evidence that high blood sugar levels contribute to a decrease in the brain’s ability to remember information and learn new information.

Malin said insulin, which is produced by the pancreas and travels to the brain to perform its functions, plays a central role in promoting cerebral blood flow and neuronal function for cognition.

“Our work suggests that therapies that target insulin action in the brain can prevent dementia,” Malin said.

In a new study, Malin and colleagues are examining whether a single bout of exercise can improve the ability of intranasal insulin to support cognitive health in older adults with obesity by measuring cerebral blood flow and neuronal extracellular vesicles. Their future plans are to conduct a long-term exercise training study evaluating improvements in the brain’s insulin sensitivity in relation to cognition in older adults.

Other Rutgers scientists who participated in the study included Michal Beeri, director of the Herbert and Jacqueline Krieger Klein Alzheimer’s Research Center at Rutgers Robert Wood Johnson Medical School; and Daniel Battillo, a doctoral candidate in the kinesiology and applied physiology graduate program. Scientists from the National Institute on Aging at the National Institutes of Health involved in the study included Dimitrios Kapogiannis, Maja Mustapic and Francheska Delgado-Peraza.