SAN FRANCISCO, Calif. — A daily brisk walk or bike ride may reduce an older person’s risk of Alzheimer’s disease, according to new research. Researchers have found that physical activity dampens inflammation in the brain, protecting against mental decline.
Lead author Dr. Kaitlin Casaletto from the University of California-San Francisco and her team note that few people will disagree that an active lifestyle is good for overall health. However, it’s been unclear how physical activity improves brain health, until now. Researchers believe the benefits may come about through decreased immune cell activation.
Dementia affects over six million people in the United States, with estimates showing that figure may rise dramatically by 2050. The number of people with the condition is steadily increasing because of increasing lifespans across the world. Within the next three decades, more than 150 million may develop the disease, researchers say.
With no cure in sight, lifestyle changes that can help ward off cognitive decline are vital.
An overactive brain may trigger dementia?
Dr. Casaletto’s says microglia, the brain’s immune cells, work by clearing out debris and foreign invaders from the brain. However, too much activity can lead to inflammation, damaged neurons, and disruptions in brain signaling. Previous studies show exercise helps reduce abnormal activation in animals, but that link wasn’t as clear in humans.
The study found exercise had the greatest benefits for those with worse disease pathology. Researchers tracked 167 older adults to examine the relationship between physical activity and microglia activation.
The team used data from the Rush Memory and Aging project, which enrolls volunteers without dementia who agree to organ donation. The participants spanned the spectrum of cognitive aging. They wore activity monitors 24 hours a day for up to 10 days straight before annual cognitive exams. The researchers also measured microglia activation and Alzheimer’s disease pathology in postmortem brain tissue analyses.
“Greater physical activity was linked to lower microglial activation,” Dr Casaletto says in a statement to SWNS. “This was particularly in the inferior temporal gyrus – a brain region hit hardest by Alzheimer’s. Physical activity had a more pronounced effect on inflammation in people with more severe Alzheimer’s pathology.”
Next, the team plans to examine if exercise interventions can alter microglia activation in AD patients.
“Physical activity relates to better cognitive aging and reduced risk of neurodegenerative disease,” the study authors write in the journal JNeurosci. “Yet the cellular and molecular pathways linking behavior-to-brain in humans are unknown.”
“We objectively monitored physical activity (accelerometer-based actigraphy) and cognitive performances in life, and quantified microglial activation and synaptic markers in brain tissue at death in older adults,” the researchers continue. “These are the first data supporting microglial activation as a physiological pathway by which physical activity relates to brain heath in humans. Though more interventional work is needed, we suggest that physical activity may be a modifiable behavior leveraged to reduce pro-inflammatory microglial states in humans.”
For healthy adults, doctors recommend at least 150 minutes of moderate exercise or 75 minutes of vigorous aerobic activity a week.
South West News Service writer Mark Waghorn contributed to this report.