How is it that exercise protects the ageing brain?
Increased flow is presumed to play a role.
There is also the triggering of happy, cannabis-like chemicals that lower stress, which has knock-on benefits.
But a new study has found that elderly people who stay physically active are producing more of a class of proteins “that enhances the connections between brain cells to maintain healthy cognition”.
These connect points are called synapses.
Researchers say that this protective effect on synapses was found “even in people whose brains at autopsy were riddled with toxic proteins associated with Alzheimer’s and other neurodegenerative diseases”.
This finding underlines the importance of people with these diseases continuing to regularly exercise, with vigour.
The study was the first of its kind
“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,” said Dr Kaitlin Casaletto, an assistant professor of neurology at the University of California San Francisco.
“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.”
Dr Casaletto is the lead author of the study, newly published in The Journal of the Alzheimer’s Association.
How the researchers made their findings
Dr Casaletto teamed up with Dr William Honer, a professor of psychiatry at the University of British Columbia and senior author of the study.
Their study uses data from the Memory and Aging Project at Rush University in Chicago.
This was a project that tracked the late-life physical activity of elderly participants, who also agreed to donate their brains when they died.
The researchers found that elderly people who remained active had higher levels of proteins that assist the exchange of information between neurons (brain cells).
This result dovetailed with Dr Honer’s earlier finding that “people who had more of these proteins in their brains when they died were better able to maintain their cognition late in life”.
To their surprise, the researchers found that “the effects ranged beyond the hippocampus, the brain’s seat of memory, to encompass other brain regions associated with cognitive function”.
Reducing the damage from toxic proteins
Most people know ‘amyloid’ and ‘tau’ are the toxic proteins that gum up the brain connections in people with Alzheimer’s disease.
Perhaps less well known is that most older adults accumulate amyloid and tau in their brains.
Dr Casaletto said that many scientists “believe amyloid accumulates first, then tau, causing synapses and neurons to fall apart”.
She previously found that “synaptic integrity” (the health of brain connections), whether measured in the spinal fluid of living adults or the brain tissue of autopsied adults, appeared to dampen 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.