When elderly people stay active, their brains have more of a class of proteins that enhances the connections between neurons to maintain healthy cognition, a new study has found.
From:
University of California San Francisco
January
7, 2022 -- This protective impact was found even in people whose brains at
autopsy were riddled with toxic proteins associated with Alzheimer's and other
neurodegenerative diseases.
"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
Kaitlin Casaletto, PhD, an assistant professor of neurology and lead author on
the study, which appears in the January 7 issue of Alzheimer's &
Dementia: The Journal of the Alzheimer's Association.
The beneficial effects of physical
activity on cognition have been shown in mice but have been much harder to
demonstrate in people.
Casaletto, a neuropsychologist and
member of the Weill Institute for Neurosciences, worked with William Honer, MD,
a professor of psychiatry at the University of British Columbia and senior
author of the study, to leverage data from the Memory and Aging Project at Rush
University in Chicago. That project tracked the late-life physical activity of
elderly participants, who also agreed to donate their brains when they died.
"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."
More Proteins Mean Better Nerve Signals
Honer and Casaletto found that elderly
people who remained active had higher levels of proteins that facilitate the
exchange of information between neurons. This result dovetailed with 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, Honer said, 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.
"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.
Synapses Safeguard Brains Showing Signs
of Dementia
The brains of most older adults
accumulate amyloid and tau, toxic proteins that are the hallmarks of
Alzheimer's disease pathology. Many scientists believe amyloid accumulates
first, then tau, causing synapses and neurons to fall apart.
Casaletto previously found that synaptic
integrity, 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. "Taken together, these two studies show the potential importance
of maintaining synaptic health to support the brain against Alzheimer's
disease."
https://www.sciencedaily.com/releases/2022/01/220107100955.htm
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