March 23, 2016

Exercise Feeds Your Head

Exercise — whether it's dancing, golfing, jogging or gardening — is perhaps the single best way to fend off dementia.

Exercise remains your best defense against Alzheimer's disease. Yet another study has found that people who exercise more are less likely to develop Alzheimer's. In fact, people who exercised the most cut their risk of Alzheimer's in half.

Back in 2010 Cyrus Raji published a study that found that people who walked six miles a week or more slowed their cognitive decline as they aged. This was true even for those who already had Alzheimer's disease; they only needed to walk about five miles a week.

Those who exercised the most were found to have a 50% lower risk of being diagnosed with either mild cognitive impairment (MCI) or Alzheimer's than those who exercised the least.

Over the years many people had told Dr. Raji they didn't like walking and wondered if some other form of exercise would work just as well. His newest study answers that question — affirmatively. The type of exercise doesn't seem to matter at all. What's important is the number of calories burned during the exercise. Even dancing works.

All 15 types of exercise tested — swimming, hiking, aerobics, jogging, tennis, racquetball, walking, gardening, mowing, raking, golfing, bicycling, dancing, calisthenics and exer-cycling — were protective against Alzheimer's disease.

Since the benefit appeared to come from the number of calories burned while exercising, it's likely that the list of effective exercises is much longer.

The authors looked at data on 876 participants from the Cardiovascular Health Study, a 30-year study of heart disease and stroke in those 65 and older. These people, age 78 on average, answered standard questionnaires about their physical activity habits, received detailed MRI brain scans which included recording the volume (size) of many regions of their brain.

When this information was correlated with their exercise activity, the team found those who exercised the most were found to have a 50% lower risk of being diagnosed with either mild cognitive impairment (MCI) or Alzheimer's than those who exercised the least.

While other studies suggest that exercise helps prevent Alzheimer's, this one went further, delving into why exercise is effective. Brain scans showed that the protective effect of exercise appears to be due to its preventing gray matter loss (shrinkage) in key areas of the brain, including the hippocampus. Even people who were diagnosed with Alzheimer's or MCI showed less brain shrinkage when they exercised more.

Dr. Raji, a radiology resident at UCLA Medical Center, who has been studying how physical activity and other factors affect the brain for many years, told TheDoctor that he especially hopes people will pay attention to the finding that exercise is beneficial even after a person has been diagnosed with a minor cognitive impairment or Alzheimer's. Once people are diagnosed with Alzheimer's, they tend to become more sedentary, the exact opposite of what this study suggests they should do.

So now there's a new reason to get up and dance.

The study appears in the Journal of Alzheimer's Disease.

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