Activity reduces Alzheimer's risk

You are less likely to get Alzheimer's disease if you're more active - and even doing the washing-up counts.

A study published in Neurology used a wrist-worn device called an actigraph to measure the total activity of 716 elderly volunteers over a period of 10 days, and then followed them for an average of three and a half years.

By measuring movement directly, Dr. Aron Buchman and colleagues at RUSH University Medical Centre have eliminated the questionnaires that were a problem for previous studies exploring the association between activity and Alzheimer's disease.  Their method also meant that they measured all movement, such as doing the washing-up, rather than just gym sessions or walking the dog.

"What we found was that people with higher levels of activity at the beginning of the study had a lower risk of developing Alzheimer's disease compared to those people with the lowest levels of activity," Dr. Buchman explained.  In fact, the 10% of participants with the lowest levels of daily activity were more than twice as likely to develop Alzheimer's over the next 3 and a half years than those in the top 10%.  This was the case even after results were corrected for age, sex, years of education, self- reported exercise and activity and the presence of a gene variant called APOE4, which is known to increase the risk of developing Alzheimer's.  

And, of the volunteers who did not develop Alzheimer's disease, the most active 10% did better in initial psychological tests to assess memory and other mental functions.  They also had a slower rate of cognitive decline compared with the bottom 10% - that is, their performance in these tests dropped less, year-on-year.  

And looking back at data previously collected from some of the same patients, the researchers also found that people with a rapid rate of cognitive decline before the study did not all end up in the low activity group.  On top of that, having low cognitive function initially did not automatically mean a more rapid drop in physical activity.  This implies that although cognitive function can be influenced by exercise, exercise is not affected by cognitive function, meaning increasing physical activity could be a potential therapeutic intervention for Alzheimer's disease.

So it seems that being more physically active, even if it's doing the housework rather than going running, is associated with a lower chance of developing Alzheimer's disease.  "What we have to do now is understand the underlying biology [so we can stop people developing Alzheimer's]," says Dr. Buchman, "but this is helpful information."