Physical activity is good for every part of your body, including your brain. Recent research suggests it may help slow the progression of Alzheimer's disease in people who are at higher risk of developing the neurodegenerative disease.
Other recent studies have found a link between exercise and improved cognitive health, and these findings suggest that people with Alzheimer's disease who are more physically active may slow cognitive decline and memory problems. But these studies are limited by a number of factors that were examined in the latest analysis.
Currently studypublished in Natural medicineScientists used a more objective way of measuring physical activity among people at higher risk of developing Alzheimer's disease and tracked signs of the disease using advanced imaging techniques to show that those who were more active had up to a 54% lower risk of cognitive decline. They also observed slower cognitive and functional decline starting at about 3,000 steps per day in people who were relatively sedentary.
The study involved about 300 people who were still cognitively normal but had a higher risk of developing Alzheimer's disease because their brain scans showed signs of Alzheimer's disease. amyloid plaquesprotein clumps that are the hallmark of Alzheimer's disease. When amyloid plaques accumulate, they begin to damage neurons involved in higher thinking and memory, and eventually lead to the accumulation of another protein, tau, which is toxic to nerve cells. In the study, researchers led by Dr. Wai-Ying Wendy Yau, a neurologist at Mass General Brigham, followed the transition from amyloid to tau as an indicator of disease progression for an average of about nine years for participants.
“We show that amyloid and physical activity seem to work together to influence tau and cognitive decline,” Yau says. “And in people who have high levels of amyloid in the brain and are at higher risk of developing tau and cognitive decline but who still have no symptoms, our study shows that high levels of physical activity may slow disease progression.”
Read more: Diet and lifestyle changes may slow the progression of Alzheimer's disease
Although people's amyloid levels did not change significantly over the study period, the accumulation of tau, an indicator of Alzheimer's disease progression, varied depending on how physically active people were. This resulted in a slower decline in cognitive function, as measured by a range of cognitive and functional tests.
Those who recorded the most average daily steps, as measured by a pedometer, reduced their rate of cognitive decline by up to 54% compared to those who were inactive. Those who were the most active also saw similar benefits in measures of functional decline, which focus more on tasks such as the ability to get dressed and perform daily activities. For the fittest people, this type of decline slowed by 51% compared to people who were inactive.
“Amyloid is a way to assess whether a person is on a trajectory to develop Alzheimer's disease,” says Dr. Jasmir Chhatwal, assistant professor of neurology at the Massachusetts General Brigham and Harvard Medical School and senior author of the study. “But even with this high risk factor for amyloid, these results suggest that physical activity may modulate the relationship between amyloid and tau. This is a critical point that affects cognitive function, since tau appears to be strongly associated with cognitive function.”
Read more: The Amazing Power of a 10-Minute Walk
The effect was especially strong among those who were sedentary and began walking daily. This is encouraging, Chhatwal says, since these are the people who are most at risk for developing rapid cognitive decline.
The study found that the benefits of exercise plateaued, so after about 5,000 to 7,500 steps per day, the decline plateaued. Still, he and Yau say the results should reassure people that even relatively little activity can benefit the brain, especially for those with sedentary lifestyles.
Yau and Chhatwal emphasize that the findings do not indicate that physical activity is a panacea for Alzheimer's disease. Instead, the results provide compelling evidence that exercise should be part of any prevention strategy for people who already have amyloid in the brain but do not yet have symptoms of the disease. For example, combining the latest anti-amyloid drugs with physical activity may be a way to stop the progression of Alzheimer's disease. And thanks to advances in detecting signs of amyloid (now through PET brain scans and increasingly through improved blood tests), more people are learning that they are at risk of the disease.
“These findings empower people to understand that there is no inevitable link between an Alzheimer's disease diagnosis and rapid cognitive decline,” Chhatwal says. “These results confirm that lifestyle factors do not necessarily simply operate at the edges of larger Alzheimer's disease processes, but may have a profound impact on how amyloid leads to cognitive decline.”
