Your Diet and Your Brain

FEBRUARY 10, 2009, 12:04 PM

Mediterranean Diet May Prevent Mental Decline

By TARA PARKER-POPE

Eating a Mediterranean diet appears to lower risk for mental decline, and may help prevent Alzheimer’s in people with existing memory problems, new research suggests.

The finding, published today in The Archives of Neurology, tracked the eating habits of 1,393 people with no cognitive problems and 482 patients with mild cognitive impairment, a preliminary state of mental decline that can sometimes signal the onset of Alzheimer’s disease or other forms of dementia. The patients were then grouped based on whether they were low, moderate or consistent followers of a Mediterranean diet. People were considered to be strong adherents to a Mediterranean-style diet if they regularly ate large amounts of fish, fruits, vegetables, legumes and monounsaturated fats like olive oil, while at the same time consuming moderate amounts of alcohol and only small quantities of meat and dairy products.

After nearly five years of follow up, about 275 people in the healthy group developed mild cognitive impairment. People who closely adhered to a Mediterranean diet had a 28 percent lower risk of developing mild cognitive impairment, compared to those whose eating habits were the least like a Mediterranean diet. Moderate followers of a Mediterranean diet showed a trend toward a 17 percent lower risk than the lowest-scoring group, although that finding wasn’t statistically significant.

A Mediterranean diet also appeared to slow decline in those already diagnosed with mild cognitive impairment. Among the 482 men and women with mild cognitive impairment at the beginning of the study, 106 developed Alzheimer’s disease about four years later. But among those who strictly adhered to the Mediterranean diet, risk of Alzheimer’s was 48 percent lower, while risk was 45 percent lower among those who ate a moderate version of the diet.

It’s not clear from the study how long the participants had been following a Mediterranean eating plan. However, the researchers said that older people tend to be fairly set in their ways and stick to eating patterns that have been established years earlier, so it’s likely the habits were established at least in middle age. The average age of study participants was 77.

Because the study was observational and not a controlled clinical trial, the association of better brain aging with the consumption of a Mediterranean diet isn’t definitive and could be explained by other factors. However, researchers note that a Mediterranean diet has already been shown to be good for the heart, and there is no risk in improving eating habits in the hope of improving brain health as well.

“We know it’s a healthy diet for other reasons,’’ said lead author Dr. Nikolaos Scarmeas, assistant professor of neurology at Columbia University Medical Center. “It makes sense for people to eat in a healthy way as soon as they can and for the longest they possibly can.’’