Alzheimer's disease is known for the knockout blow it delivers to memory and other cognitive functions. But this disease of the brain may also be linked to muscle weakness, according to a study published today in the Archives of Neurology. Among the 900 older adults in the study, those who were initially stronger had a smaller chance of getting Alzheimer's in the future. (The average follow-up time was 3.6 years.) Muscle strength was also tied to a lower risk of developing mild cognitive impairment, the precursor to Alzheimer's disease, the study found.
As tempting as it is to yell from the hilltops that hitting the gym prevents Alzheimer's, this study wasn't designed to tell if there's a causative effect, says Patricia Boyle, a neuropsychologist with the Rush Alzheimer's Disease Center in Chicago and an author of the study. It's looking like one degenerative process drives both conditions, and it shows up first as muscle weakness before manifesting itself as cognitive problems. That common danger may be damage to the mitochondria—the cells' energy factories—or central nervous system disorders like stroke, the study authors say. Or, the same accumulations of plaques and tangles in the brain that are characteristic of Alzheimer's disease may be responsible. "We know they cause cognitive problems, but there's increasing evidence that they cause motor dysfunction," says Boyle. That suggests that screening older folks for muscle strength may offer a way to identify who is most at risk of the disease, she says.
But even if this study doesn't directly point to weightlifting as a sure way to keep Alzheimer's disease at bay, there's plenty of other evidence suggesting that aerobic exercise can help preserve brain function as you age. The authors of a review published in June by the Association for Psychological Science said studies "overwhelmingly" indicate that exercise specifically helps people with executive functioning (things like planning ahead), short-term memory, and focusing and maintaining attention.
It appears, in fact, that exercise not only slows negative changes to the brain but also gives you some cognitive reserves. So even if those plaques appear, they don't have the cognitive impact that they would in a nonexerciser.
[Look at a slide show featuring 5 other ways to protect yourself against Alzheimer's and dementia.]
Meantime, strength training has a multitude of benefits for older (and younger, and middle-aged) folks. It can help stave off age-related muscle loss, known as sarcopenia, as well as osteoporosis. Larger muscles may even protect the body from diabetes and, eventually, heart disease by increasing the body's ability to use insulin to help process glucose. The bottom line from the totality of research we have: A balanced exercise plan incorporating aerobic workouts, as well as strength, flexibility, and balance training, is great for almost everyone.
[Take a look at this slide show of 10 excuses for not exercising and why they won't fly, then speed-walk yourself over to our 10-week workout and get started.]
Check it out: That's Fit gets to test out the AlterG antigravity treadmill, which looks like a hoot to use but sadly is out of the price range of most casual exercisers. And Marion Nestle's Food Politics blog takes a victory lap after Kellogg's says it will phase out claims that Cocoa Krispies supports your childs immunity.