Study Shows Exercise Can Strengthen Neural Connections in the Aging Brain to Maintain Cognitive Health

We’ve long known that physical activity is good for the mind and body. Now, researchers at the University of California San Francisco (UCSF) have found that exercise can change the chemistry of the brain to promote stronger connections between neurons in older adults. As a result, elderly people who remain active can maintain brain health and prevent cognitive decline.

The protective effect was seen even in people with dementia and neurodegeneration associated with conditions like Alzheimer’s disease.

The study looked at several synaptic proteins in the brain involved in maintaining healthy communication between neurons. The researchers found that older individuals who exercised had higher levels of these proteins. Additionally, the effects of these proteins were able to counter the negative effects of toxic proteins in the brain associated with dementia and Alzheimer’s like the tau protein and beta-amyloid.

The study was published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association last week.

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While the positive effects of exercise on cognitive health have been shown in animal models, it has been more difficult to demonstrate in humans.

Previous studies have shown that physical activity can reduce the risk of dementia by 30 percent to 80 percent; however, the biology underlying this has remained unknown.

“Our work is the first that uses human data to show that synaptic protein regulation is related to physical activity and may drive the beneficial cognitive outcomes we see,” Kaitlin Casaletto, PhD, an assistant professor of Neurology and lead author on the study, said in a UCSF news release.

“Maintaining the integrity of these connections between neurons may be vital to fending off dementia, since the synapse is really the site where cognition happens,” Casaletto said. “Physical activity — a readily available tool — may help boost this synaptic functioning.”

Key Brain Proteins Maintain Cognitive Health

Casaletto worked with William Honer, MD, a professor of psychiatry at the University of British Columbia and senior author on the study, on the research. Casaletto and Honer used data from the Memory and Aging Project at Rush University in Chicago, which tracked the physical activity of elderly participants in the later years of their lives. The individuals also consented to donating their brains when they died.

The researchers looked at several synaptic proteins involved in neuronal communication, including synaptophysin, synaptotagmin-1, vesicle-associated membrane proteins, syntaxin, complexin-I and complexin-II. They found that people who remained active had higher levels of the proteins.

“The more physical activity, the higher the synaptic protein levels in brain tissue. This suggests that every movement counts when it comes to brain health,” Casaletto said.

Additionally, the researchers found that the effects extended beyond the hippocampus, the brain structure involved in memory and learning, to other brain regions associated with cognitive function, which came as a surprise, Honer said.

“It may be that physical activity exerts a global sustaining effect, supporting and stimulating healthy function of proteins that facilitate synaptic transmission throughout the brain,” Honer said.

This finding corroborates some of Honer’s previous work, which showed that people who had higher levels of the neuronal proteins were better able to maintain their cognitive health later in life.

Moreover, Casaletto previously found that synaptic integrity appeared to weaken the relationship between amyloid and tau, and between tau and neurodegeneration.

“In older adults with higher levels of the proteins associated with synaptic integrity, this cascade of neurotoxicity that leads to Alzheimer’s disease appears to be attenuated,” she said. “Taken together, these two studies show the potential importance of maintaining synaptic health to support the brain against Alzheimer’s disease.”

So how much physical activity is needed to increase levels of good brain proteins to maintain cognitive health?

“We recommend aiming for 150 min/week [2.5 hours/week] of physical activity. Prior studies have shown that even walking relates to reduced risk of cognitive decline!” Casaletto told CNN.