Physical activity might not ward off dementia
By Lisa Rapaport
(Reuters Health) - Middle-aged adults who are inactive may be more likely to develop early-onset dementia than people who exercise, but getting them to be active is unlikely to prevent the problem, a recent study suggests.
That's because the link with dementia may be due more to inactive adults' increased risk of heart disease, diabetes, and stroke, researchers say.
The research team examined data from 19 previous studies with about 405,000 participants who were 46 years old on average and followed for an average of 15 years. At the start of these studies, none of these people had dementia and 41 percent of them were inactive.
Over the first decade of follow-up, sedentary people were 40 percent more likely to develop dementia, the study found. During this period, inactive people were also more prone to cardiometabolic disorders like stroke, diabetes, and heart disease than regular exercisers.
As more time passed, inactivity was still tied to a higher risk of cardiometabolic diseases. But there was no longer a meaningful connection between inactivity and dementia.
"I believe physical activity is very important for health and our results support a physically active lifestyle as a way to reduce the risk of cardiometabolic disease," said lead study author Mika Kivimaki of the University College London in the U.K. and the University of Helsinki in Finland.
"But in light of the current evidence, intervention strategies targeting physical inactivity alone will have limited effectiveness for dementia prevention," Kivimaki said by email.
Overall, a total of 2,044 people developed dementia during the study, including 1,602 cases of Alzheimer's disease.
One limitation of the study is that researchers only looked at activity levels at a single point in time, which doesn't capture the cumulative effects of a sedentary lifestyle, researchers note in the BMJ.
Researchers also relied on data from electronic medical records to identity dementia cases, and it's possible this may have left out some people with milder cases.
Still, exercise combined with healthy eating habits and lifestyle choices can improve cognitive abilities in both healthy adults and people with early signs of cognitive decline, said James Blumenthal, a psychiatry professor at Duke University Medical Center in Durham, North Carolina. What's less clear is whether improving cognitive function can help prevent or delay the development of dementia.
"While the jury may be out as to whether physical activity reduces the risk of dementia, there is overwhelming evidence for the value of physical activity for reducing risk for adverse cardiovascular events--heart attack, stroke, diabetes and for improving overall health," Blumenthal, who wasn't involved in the study, said by email.
"Adoption of healthy lifestyles, including physical activity, especially for inactive adults or individuals with cardiovascular risk factors, may represent one effective strategy for not only improving heart health but also for improving brain health," Blumenthal added.
SOURCE: http://bit.ly/2W9roNY BMJ, online April 17, 2019.
