Scientists have discovered that specific cells in the brain, which play a role in how the body reacts to insulin, become activated after exercising. This finding implies that physical activity may have a direct positive effect on brain function.
Researchers from Rutgers University-New Brunswick have found that unique cells related to insulin response are triggered in the brain following physical exercise, hinting that active lifestyles might enhance cognitive abilities.
According to a study published in Aging Cell, a journal dedicated to aging biology, there is potential for developing therapies that target insulin actions to either slow down or prevent the progression of dementia.
“We think this research is significant because it implies that exercise might enhance thinking and memory by improving how insulin works in the brain,” stated Steven Malin, an associate professor in the Department of Kinesiology and Health at Rutgers and the study’s lead author.
This research, conducted in partnership with the National Institutes of Health’s National Institute on Aging, examined the function of neuronal extracellular vesicles, which are specialized cells released by the brain.
Extracellular vesicles, previously regarded as “cell dust,” have gained considerable recognition over the last 15 years as essential components in the microcosm of the human body, playing a vital role in transporting important molecules, like proteins, between cells. In this study, scientists focused on vesicles produced in the brain that carry several proteins linked to insulin sensitivity, notably one called Akt.
Insulin sensitivity indicates how effectively the body utilizes insulin, which is crucial for regulating blood sugar levels. Individuals with high insulin sensitivity can more efficiently use blood glucose, particularly in muscle tissues, leading to decreased blood sugar levels. Conversely, those with diabetes—characterized by low insulin sensitivity or insulin resistance—often have brain cells that are less responsive to insulin, adversely affecting cognitive function.
In their study, researchers isolated the vesicles found in the blood of participants. The experiment lasted two weeks and involved 21 volunteers, averaging 60 years old, all diagnosed with prediabetes. The participants completed 12 supervised exercise sessions, each lasting 60 minutes at moderate to high intensity. They consumed a glucose drink both before and after exercising, and blood samples were collected before and after the training sessions.
Analysis of the blood samples revealed an increase in the number of neuronal vesicles transporting proteins related to insulin sensitivity after each training session, particularly highlighting Akt.
“This marks our first demonstration that exercise influences insulin signaling through neuronal extracellular vesicles and correlates with clinical improvements in blood sugar control,” Malin explained. “We view these vesicles as indicators of brain insulin sensitivity.”
This suggests that exercise may enhance the brain’s ability to respond to insulin, benefiting neuronal function.
Insulin is increasingly acknowledged for its role in cognitive regulation, encompassing mental processes such as learning and sensory experience. Prediabetes is a significant health issue characterized by elevated blood sugar levels that are not yet high enough for a Type 2 diabetes diagnosis. Individuals with prediabetes face the risk of insufficient insulin levels, especially in the brain, raising the odds of developing dementia-related conditions like Alzheimer’s, according to Malin.
Insulin is also vital for memory creation, retrieval, processing speed, and synaptic functioning, which are necessary for intercellular communication in the brain.
“If insulin levels in the brain are low, brain cells can become dysfunctional and fail to interact effectively,” Malin noted. “It’s akin to playing a game of telephone; as the message passes on, it can get lost when the brain becomes insulin resistant.”
While it’s long been suspected that exercise enhances cognition, the underlying processes were unclear. Previous research has shown that elevated blood sugar can diminish the brain’s ability to recall and learn new information.
Malin emphasized that insulin, produced by the pancreas and transferred to the brain, is crucial for increasing blood flow to the brain and supporting cognitive functions.
“Our findings imply that developing therapies focused on brain insulin action might help prevent dementia,” Malin stated.
In a forthcoming study, Malin and his team will investigate whether a single session of exercise can boost the effectiveness of intranasal insulin in supporting cognitive health among obese older adults by analyzing brain blood flow and neuronal extracellular vesicles. They also plan to embark on a long-term study assessing improvements in brain insulin sensitivity in relation to cognitive function in older adults.
Other Rutgers researchers involved in this study included Michal Beeri, the director of the Herbert and Jacqueline Krieger Klein Alzheimer’s Research Center at Rutgers Robert Wood Johnson Medical School, and Daniel Battillo, a Ph.D. candidate in the kinesiology and applied physiology program. Collaborators from the National Institute of Health’s National Institute on Aging included Dimitrios Kapogiannis, Maja Mustapic, and Francheska Delgado-Peraza.
