How does exercise keep your brain young?
By Kelly Servick, Sep. 6, 2018.
“Stay active; age gracefully. Behind this truism, there’s a pile of unanswered scientific questions. Researchers are still sorting out what it is about physical activity that seems to lower the risk of dementia later in life. Even more uncertain is whether the effects of exercise can alter the course of diseases that cause dementia—chief among them, Alzheimer’s disease—once they’ve already taken root.
A study published today in Science offers some new clues. In mice that mimic a severe, genetic form of Alzheimer’s disease, a combination of treatments that prompt the growth of new brain cells and protect them from damage can mimic the beneficial effects of exercise (http://science.sciencemag.org/content/361/6406/eaan8821) in preventing memory decline. So could we someday bottle the effects of exercise to treat Alzheimer’s? And if so, what exactly would we need to bottle? Here’s a rundown of what we know, and what’s still controversial.
What’s the link between exercise and brain aging?
Many large studies suggest staying active and fit throughout life lowers the risk of memory problems later on. For example, a recent project tracked more than 1000 Swedish women over 4 decades and found that for those judged to have “high” cardiovascular fitness on entering the study—as measured by the maximum workload they could handle on a stationary cycle machine before exhaustion—the onset of dementia was delayed (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5894933/), on average, by 9.5 years compared to those with “medium” fitness. But such studies can’t rule out all other confounding factors that might influence dementia risk—from genes to other aspects of a healthy lifestyle common in regular exercisers. And they don’t explain what exercise actually does to the brain.
Does exercise fight the effects of Alzheimer’s disease once someone has it?
Evidence for this is stronger in rodents than in humans.” …….continued….….