Two studies published in this month’s Journal of the American Medical Association add to evidence that long-term lifestyle habits may reduce the risk of mental decline in old age. These studies are observational and not definitive, but they hint at what might reduce the chances of Alzheimer’s or dementia.
The first study – entitled “Physical Activity, Diet, and Risk of Alzheimer Disease” – was a long-term look at 1,880 elderly people in New York City, and found that a Mediterranean-type diet and physical activity each were linked to less risk for Alzheimer’s disease. Marked by high consumption of foods such as vegetables, legumes and cereals, served with olive oil, in addition to moderate fish and alcohol intake, the traditional diet has long conferred better cardiovascular health. Those who adhered most closely to the diet reduced their risk for Alzheimer’s by 40%, while those with the highest physical activity decreased their risk 33%, compared with people who didn’t adhere closely to the diet or were not physically active.
The second study – published as “Adherence to a Mediterranean Diet, Cognitive Decline, and Risk of Dementia” – was a shorter-term observation of 1,410 patients in France, and found some correlation between a Mediterranean-type diet and slower cognitive damage. Subjects who adhered to the Mediterranean-type diet experienced a slower rate of mental decline than those who did not eat the diet, but did not prove a link for dementia, which requires a clinical assessment of a variety of mental and social functions.
Doctors in the field are careful to note that none of these findings demonstrate a causal relationship, but instead reflect the advantages of a continual healthy lifestyle. “The benefits don’t just occur at age 70 when you suddenly stop eating McDonald’s and start eating Brussels sprouts,” says David Knopman, a neurologist at the Mayo Clinic in Rochester.
For now, Dr. Scarmeas, the author of the first study, says his studies strongly suggest that a Mediterranean diet and exercise both confer independent and positive health benefits. But together, they are even better. “The relative risk reduction for Alzheimer’s is about 60% when you combine the diet and exercise,” he says.