Exercise, Alzheimer’s and Fruit

The National Runners’ and Walkers’ Health Study found that running lowered the risk of dying from (or with) Alzheimer’s during the study period by as much as 40 per cent for the group doing the most exercise. I decided to dig a little further into that topic.

No matter how you spin it, the news that exercise may help prevent and treat Disease X doesn’t really qualify as a surprise. That’s the default assumption these days.

But when Disease X is Alzheimer’s, a progressive and irreversible degenerative brain condition with few effective treatment options, the finding is worth a closer look. Drawing on data from more than 150,000 participants in the National Runners’ and Walkers’ Health Studies over a 17-year period, a new U.S. study shows that regular exercise lowers the risk of dying from Alzheimer’s by as much as 40 per cent – an indication that the disease’s progression is not unchangeable…

A few additional thoughts to add. According to a report from the Ontario Brain Institute, if everyone met the government’s recommended exercise guidelines of 150 minutes of moderate exercise per week, about 1 in 7 cases of Alzheimer’s would be avoided. That report was based on a review of more than 800 studies, of which 45 were considered high-quality. So the idea that exercise can help prevent or delay Alzheimer’s isn’t new. But what the latest study adds is a dose-response effect – not only is hitting the guidelines good, but doing more is even better. The highest-exercise group in the new study was doing the equivalent of at least 25 kilometres a week of running, which works out to about double the guidelines.

So why does exercise help the brain? One of the researchers I spoke to gave three possible reasons:

1. Exercise boosts cardiovascular health through mechanisms like improved blood flow to the brain – “so if your heart is healthy, your brain is healthy,” he says.
2. Exercise also boosts levels of brain-derived neurotrophic factor, which stimulates the growth of new neurons and their integration into the network of existing neurons.
3. There’s also recent evidence that exercise stimulates the production of a protein that helps protect the brain from stress-related damage linked to depression, which often accompanies Alzheimer’s.

And as a bonus, the researchers also collected (as part of their intake survey) information about fruit consumption. Turns out it’s an even better predictor of Alzheimer’s mortality than exercise!

Of course, fruit consumption is likely just a marker for other dietary (and perhaps lifestyle) habits, so it’s impossible to draw any specific conclusions from this. Still, it’s a good reminder that what you eat may well have lasting effects, and not just on your waistline and heart.