Q: In your book, you cite a study showing that moderate exercise, like daily brisk walks, can lower a person's risk for Alzheimer's disease by 45 percent. Is it that simple?
A: When your heart is really pumping, you deliver more nutrients and oxygen to your brain. And the body secretes protective chemicals during physical activity—including a protein called brain-derived neurotrophic factor, which is thought to spark the growth of neurons. Exercise can't guarantee that you won't get Alzheimer's, of course. But the hope is to delay the disease long enough so that you never experience symptoms in your lifetime.
Q: Is there any validity to the claim that brain games and puzzles can boost mental performance?
A: The brain fitness industry is expected to be worth at least $2 billion by 2015, but it hasn't quite figured out its standards. Although doing crossword puzzles is associated with a lower risk of Alzheimer's, there's no absolute proof. But generally, anything that gets your brain working is good.
Q: I've heard that repetitive mental exercises aren't as helpful as unfamiliar ones. Is that true?
A: Yes. Once a task becomes repetitive, the brain work involved becomes more rote, which means there's less neural activity going on—and neural activity that forms new pathways is something we think protects the brain. So you want to aim for that sweet spot where the mental exercise is difficult yet not too stressful. Because stress works against your memory. Dr. Robert Sapolsky, a neuroscientist at Stanford, has found that small animals under chronic stress have fewer neurons in the hippocampus, a memory center of the brain. In people, stress has been found to impair learning and recall. Fortunately, it's only temporary: Once you relax, your brain bounces back.
Q: What about caffeine—good or bad?
A: A 2009 study done in Finland found that subjects who drank three to five cups of coffee a day had a 65 percent lower risk of dementia and Alzheimer's. But too much coffee makes it hard to sleep, and sleep is important for brain health. Moderation is key.
Q: If you had to pick one tip as the most important thing a person can do to prevent Alzheimer's, what would it be?
A: Physical exercise. The evidence is so compelling. Number two would be mental exercise. Even driving home by new routes can help.
Q: And you really think a single change can make a difference?
A: According to our data, if everyone in the United States adopted one additional healthy lifestyle habit, the number of expected Alzheimer's cases would be reduced by a million in the next five years. So yes, I do.
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