Being more physically active and adhering to a Mediterranean-type diet appears to be associated with reduced Alzheimer's disease risk.

According to a study, elderly individuals who had a diet that included higher consumption of fruits, vegetables, legumes, cereal and fish and was low in red meat and poultry and who were physically active had an associated lower risk of Alzheimer disease.

Research regarding the effect physical activity can have on the risk of Alzheimer disease or dementia has shown mixed results, as has the effect of dietary habits. Their combined association has not been investigated.

Nikolaos Scarmeas and colleagues examined the association between physical activity and risk of Alzheimer disease and also the effect of physical activity and adherence to a Mediterranean-type diet on Alzheimer disease risk. The study included 2 groups that consisted of 1,880 community-dwelling elderly residents of New York city without dementia at the start of the study, for whom there was both diet and physical activity information available. Standardized neurological and neuropsychological measures were administered approximately every 1.5 years from 1992 through 2006.

The participants received measurements of their adherence to a Mediterranean-type diet (scale of 0-9; categorized as low, middle, or high) and their physical activity (sum of weekly participation in various physical activities, weighted by the type of physical activity [light, moderate, vigorous]; categorized into no physical activity, some, or much, also low or high), separately and combined. A higher score for diet was obtained with higher consumption of fruits, vegetables, legumes, cereals, and fish; lower consumption of meat and dairy products; a higher ratio of monounsaturated fats to saturated fats and mild to moderate alcohol consumption.

Individuals were followed up for an average of 5.4 years, during which a total of 282 developed Alzheimer disease. In considering only physical activity, the researchers found that more physical activity was associated with lower risk for developing Alzheimer disease. "Compared with physically inactive individuals, report of some physical activity was associated with a 29 percent to 41 percent lower risk of developing Alzheimer disease, while report of much physical activity was associated with a 37 percent to 50 percent lower risk," the authors write.

When considered simultaneously, both physical activity and Mediterranean diet adherence were significantly associated with Alzheimer disease incidence. According to the researchers, "Belonging to the middle diet adherence tertile was associated with a 2 percent to 14 percent risk reduction, while belonging to the highest diet adherence tertile was associated with a 32 percent to 40 percent reduced risk. Similarly, compared with individuals with no physical activity, individuals reporting some physical activity had a 25 percent to 38 percent lower risk for Alzheimer disease, while individuals reporting much physical activity had a 33 percent to 48 percent lower risk for Alzheimer disease."

The authors also write, "Compared with individuals with low physical activity plus low adherence to a diet (absolute Alzheimer disease risk, 19 percent), high physical activity plus high diet adherence was associated with a 35 percent to 44 percent relative risk reduction (absolute Alzheimer disease risk, 12 percent). … Absolute Alzheimer disease risks declined from 21 percent in the group with no physical activity plus low diet adherence to 9 percent in the group with much physical activity plus high diet adherence."

The authors further noted that even low degrees of physical activity reported by these elderly study subjects seemed to be associated with having a protective effect against Alzheimer's

"This study is important because it shows that people may be able to alter their risk of developing Alzheimer's by modifying their lifestyles through diet and exercise"

"In summary, our results support the potentially independent and important role of both physical activity and dietary habits in relation to Alzheimer disease risk. These findings should be further evaluated in other populations."
References:
1. Nikolaos Scarmeas, et al. Physical Activity, Diet, and Risk of Alzheimer Disease. JAMA. 2009;302(6):627-637.