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New evidence that physical activity can forestall the mental decline in aging brains

More people are living longer these days, but the bad news is the large increase in cases of age-related mental decline. By some estimates, the global incidence of dementia will more than triple in the next 35 years. That grim prospect is what makes a study published in March in The Journal of Alzheimer’s Disease so encouraging: It turns out that regular, walking, cycling, swimming, dancing and even gardening may substantially reduce the risk of Alzheimer’s.

Exercise has long been linked to better mental capacity in older people. Little research, however, has tracked individuals over years, while also including actual brain scans. So for the new study, researchers at the University of California, Los Angeles, and other institutions analyzed data produced by the Cardiovascular Health Study, begun in l989, which has evaluated almost 6,000 older men and women. The subjects complete medical and cognitive tests, fill out questionnaires about their lives and physical activities and receive M.R.I. scans of their brains. Looking at nearly ten years of data from nearly 900 participants who were at least 65 upon entering the study, the researchers first determined who was cognitively impaired, based on their cognitive assessments. Next they estimated the number of calories burned through weekly exercise, based upon the participants’ questionnaires.

The scans showed that the top 25 per cent of active individuals proved to have substantially more grey matter, compared with their peers, in those parts of the brain related to memory and higher thinking. More grey matter, which consists mostly of neurons, is generally equated with greater brain health.  At the same time, those whose physical activity increased over a 5 year period—though these cases were few—showed notable increases in grey matter volume in those same parts of their brains. And, even more importantly, people who had more grey matter correlated with physical activity also had a 50 per cent less risk five years later of having experienced memory decline or of having dementia or Alzheimer’s.

“For the purposes of brain health, it looks like it’s a very good idea to stay as physically active as possible,” says Cyrus Raji, a senior radiology resident at U.C.L.A., who led the study. He points out the “Physical activity” is an elastic term in this study: It includes walking, jogging, moderate cycling, gardening and even ballroom dancing as well as other calorie-burning recreational pursuits.  Raji said he hopes that further research might show whether this caloric expenditure is remodeling the brain, perhaps by reducing inflammation or vascular diseases.

The amount and type of activity for staving off memory loss is unknown, although even the most avid exercisers in this group were generally cycling or dancing only a few times a week. Still, the takeaway from this study is that physical activity might change the way we age. We still might get a day older each day, but at least we have the capacity to at least maintain or even increase our mental capacity for memory and alertness.

If you want to live a long time, but keep your memories, your thought processes, and your reflexes and enjoy the quality of life every day, then just keep on moving.

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