October 13, 2010
Walk To Cut Memory Decline In Half
6 to 9 miles per week will reduce the rate of loss of gray matter volume and lower risk of memory problems.
For the study, 299 dementia-free people recorded the number of blocks they walked in one week. Then nine years later, scientists took brain scans of the participants to measure their brain size. After four more years, the participants were tested to see if they had developed cognitive impairment or dementia.
The study found that people who walked at least 72 blocks per week, or roughly six to nine miles, had greater gray matter volume than people who didn't walk as much, when measured at the nine-year time point after their recorded activity. Walking more than 72 blocks did not appear to increase gray matter volume any further.
By four years later, 116 of the participants, or 40 percent, had developed cognitive impairment or dementia. The researchers found that those who walked the most cut their risk of developing memory problems in half.
If you walk 3 miles per hour then that's about 2 to 3 hours walking per week. You doing that? if not, what could you add to your routine to get that amount of walking in per week?
Corr/caus, I would beg. There are a lot of associations with Alz, at least on that is present years (like a decade) before clinical onset. I believe weight has been found to be low like a decade and more before diagnosis, though who knows if that was widely confirmed. I'll bet at least some of the associations are at least partly non-causal. There are several other diseases that often show a few phenomena at least a couple years prior to diagnosis.
But of course, that's not to deny that this could well be all or almost all causal.
I agree. If I had to bet, I would guess that this is a classic missing variable situation where some third factor is affecting both walking and dimentia. For example social class or health consciousness. Heck, it's even possible that brain atrophe makes people lazier.
My father was a walker, if not 6-9 miles per week, and developed Alzheimers in his later 60's. His mother had similarly sucumbed to dementia.
At 60, I am preparing to run two marathons in the first quarter of next year, after laying off for a year. I catch myself forgetting things now and then, no worse than usual.
It appears that whatever a body can do to promote blood circulation usually pays off well. Also, dietary impacts should not be ignored. The China Study, by Campbell, is a good start. As we age it appears our bodies benefit substantially by drawing our protein and fat requirements from vegetable sources, not animal. Campbell says to go vegetarian at least, but some of the graphs show Pareto's principle at work, moderate change can produce substantial benefit, while huge change doesn't seem to buy much more improvement.
Oh, and don't forget Linus Pauling, you need at least two grams of Vitamin C per day...
Hmm, if I'm reading this correctly, they're talking about six to nine miles total a week. Judging from when I've worn a pedometer, that's nothing. Even a sedentary office worker would hit that just with normal daily activity.
Digging further, I found the abstract and it turns out that mean age of the participants was 78:
I'm going to have to agree with Sycamore that causation is being confused here. I suspect that individuals in their 70's who walk the most are the ones that are most healthy to begin with. It's not that walking has a protective effect but that mental deterioration has a debilitating effect. The full study is unfortunately behind a pay wall so I can't read it to determine if the researchers discuss this.