When it comes to memory, there might just be something to the old adage "use it or lose it." Writing in the February 13 issue of the Journal of the American Medical Association, researchers provide further evidence that people who participate more frequently in cerebrally challenging activities have a decreased risk of developing Alzheimer's disease.

Robert S. Wilson of the Rush Alzheimer's Disease Center and colleagues examined more than 700 participants in the Religious Orders Study, a group of Catholic nuns, priests and brothers who have agreed to annual memory testing and brain donation at the time of death. At the study's outset, the subjects underwent cognitive testing and filled out a questionnaire probing the amount of time they spent engaged in common pastimes involving information processing: watching TV, listening to the radio, reading, playing games or solving puzzles and going to museums. Participation frequency was rated on a five-point scale ranging from every day (five points) to once a year or less (one point). The scientists followed the subjectsall age 65 or older and dementia free at the start of the studyfor an average of 4.5 years and administered annual follow-up cognitive tests.

Over a seven-year period, 111 participants developed Alzheimer's disease. The researchers found an inverse correlation between the frequency of cognitive activity and the risk of developing the disease. For each one-point increase in a subject's score on the scale of intellectual activities, they report, the risk of developing the disease decreased by 33 percent. Moreover, people with the highest frequency of activity had a 47 percent lower risk of disease compared with those with the lowest activity level.

The precise mechanisms governing such an association between mental stimulation and reduced risk of Alzheimer's disease remain unclear. Some scientists propose that the tasks afford protection by making the brain more efficient and therefore less vulnerable to the damage wreaked by Alzheimer's. Others suggest that frequent mind flexing strengthens processing skills and allows the brain to compensate for age-related declines. It is also possible that people who develop Alzheimer's may be less inclined, years earlier, to engage in cognitively stimulating activity. "Further research," says Elisabeth Koss, assistant director of the National Institute on Aging's Alzheimer's Disease Centers Program, "should help better sort out whether cognitive activities can be prescribed to reduce risk of Alzheimer's disease and why that may be so."