Q: I keep reading about disappointing drug trials to help prevent and treat Alzheimer's disease. What else can I do to reduce my risk?
A: A few decades ago, the state of our brain was believed to be beyond our control. Conventional wisdom taught that people are born with a certain number of brain cells, which die over time and are not replaced.
But recent research has dramatically changed that thinking. While it remains true that the areas of the brain associated with memory and reason tend to shrink with age, you can add still add brain cells and build new connections between those cells throughout your life.
Although the news regarding pharmaceutical discoveries for dementia has been disappointing, we have learned that taking four actions now can reduce the risk of cognitive decline.
Physical exercise. The best evidence so far is for aerobic exercise and physical fitness. Not only have scores of observational studies linked regular aerobic exercise to reduced risk of dementia, the results of several randomized controlled clinical trials indicate that aerobic exercise improves memory and reasoning ability. In addition, some brain imaging studies suggest that regular exercise might even increase brain size.
In studies of healthy people, an average of 30 minutes of aerobic exercise five times per week led to cognitive benefits. Recent research suggests that putting in more hours per week of exercise, including fitness training, might improve brain health even more.
There is also some evidence that mastering more complicated physical activities, like dance or sports, has greater benefits than repeating simpler ones, like walking.
Mediterranean style diet. The Mediterranean style diet -- high in fruits, vegetables, whole grains and legumes; moderate in olive oil and unsaturated fats, cheese and yogurt; and low in red meat -- has been a mainstay of cardiac prevention for almost 20 years. More than a dozen observational studies have shown that it is also associated with a reduced risk of dementia. In those investigations, people who adhered to the diet most closely had the greatest reduction in risk.
Social connectedness. Evidence from observational studies has linked a reduced risk of dementia with social connectedness dating back to the 1990s. As researchers have looked into these connections more deeply, they have discovered that variety and satisfaction in social contacts is more important than the size of a person's social network.
Mental stimulation. There is some evidence that challenges like playing a musical instrument or learning another language have more benefits than repetitive exercises like crossword puzzles. Whether "brain-training" programs actually improve memory or reasoning ability has not been proven. Getting together with family and friends to play cards may be as good as or even better than playing brain games.
(Howard LeWine, M.D., is an internist at Brigham and Women's Hospital in Boston and assistant professor at Harvard Medical School. For additional consumer health information, please visit www.health.harvard.edu.)