Last year we learned that a Mediterranean diet coupled with exercise reduced the risk for Alzheimer’s by an impressive 60%. Now, researchers have followed up on this concept by looking at how the diet actually affects the brain’s aging process in seniors who eat a classic Mediterranean diet.

The team followed over 4,000 seniors in the Midwest, both Caucasian and African-American, who varied in their eating habits. They assigned people a "MedDiet" score according to how close their eating habits were to those of a typical Mediterranean diet, which is high in fish, whole grains, veggies, fruits, low-fat dairy, nuts, and wine, and low in red meat, refined sugars, and high-fat dairy products.

Researchers say that for two people of the same age, the person who had a MedDiet score 10 points higher than the other would perform cognitively as if he or she were three years younger.

The researchers were also interested in the role of wine in diet and in cognitive decline, so they also gave the participants on their "MedDiet wine score" which took into account whether they preferred wine over other forms of alcohol.

The participants were followed for almost eight years, on average, and their cognitive abilities were tested four times during this period.

Out of a possible MedDiet high score of 55, the highest score attained in the study was 45. The average score was 28. People who stuck most closely to the Mediterranean diet were much less likely to suffer from cognitive decline than those whose scores were lower, reflecting a diet high in saturated fats and low in fruits and vegetables. In fact, the researchers say that for two people of the same age, the person who had a MedDiet score 10 points higher than the other would perform cognitively as if he or she were three years younger.

Interestingly, people who had the highest MedDiet wine scores also had slower rates of cognitive decline than those who scored lowest. This finding is in line with a host of other research, suggesting that a little wine has significant benefits to the body and brain.

While there are still many questions about the mechanism, the thought is that Mediterranean diet reduces oxidative stress and inflammation in the body, which may be responsible for the reduced risk of cognitive decline seen here and in other studies. While just how the Mediterranean diet works is still up for debate, the fact that it works is not. So adding some olive oil, whole grains, and veggies to the diet is likely a good idea any way you slice it.

The research was carried out by researchers at Rush University Medical Center, and published in the December 22, 2010 online issue of The American Journal of Clinical Nutrition.