March 9, 2009
A Mediterranean-style diet rich in fruits, vegetables, whole grains and unsaturated fats appeared to lower the risk of mild cognitive impairment, a form of memory loss that often precedes Alzheimer's disease. Men and women who ate the heart-healthy diet who had mild cognitive impairment were also less likely to develop Alzheimer's disease, the research found.
The findings provide further evidence that consuming lots of fish, vegetables, legumes, fruits, cereals and unsaturated fats, like the kind found in olive oil or fish oils, is good for the brain. The Mediterranean diet, named for the traditional diet of countries like Greece and Italy along the Mediterranean sea, also tends to be low in dairy products and red meat, and includes a moderate amount of red wine.
"Among behavioral traits, diet may play an important role in the cause and prevention of Alzheimer's disease," the authors, from Columbia University Medical Center in New York, wrote. The findings appeared in the medical journal Archives of Neurology.
Previous studies from these researchers and others have shown that people who eat a Mediterranean diet have a lower risk for Alzheimer's disease. In the current study, researchers monitored 1,393 men and women who had no memory or thinking problems as well as 482 who had mild cognitive impairment, a more serious condition than the "senior moments" that many older people complain of as they age, but not as serious as the memory loss or other symptoms associated with Alzheimer's.
Participants filled out an extensive food questionnaire, and also underwent periodic exams and memory tests. They were put into groups according to how closely their diets followed the Mediterranean style of eating.
After an average of 4.5 years, 275 of the 1,393 participants who did not have mild cognitive impairment, or M.C.I., developed the condition. Those whose diets most closely followed a Mediterranean plan were 28 percent less likely to develop M.C.I. than those whose eating veered most from the heart-healthy diet. Those who adhered less strongly to a Mediterrean diet had a 17 percent lower risk.
Among the 482 with mild cognitive impairment at the beginning of the study, 106 developed Alzheimer's disease over an average 4.3 years of follow-up. Adhering to the Mediterranean diet also was associated with a lower risk for this transition. The one-third of participants with the highest scores for Mediterranean diet adherence had 48 percent less risk, and those in the middle one-third of Mediterranean diet adherence had 45 percent less risk than the one-third with the lowest scores.
The Mediterranean diet may improve cholesterol levels, blood sugar levels and blood vessel health overall, or reduce inflammation, all of which have been associated with mild cognitive impairment. These factors have also been implicated in Alzheimer's disease.
Earlier studies have shown that a Mediterranean diet may cut the risk of heart disease, cancer, diabetes and possibly other ills as well. This study adds to a growing body of research that such a diet may help keep the brain young as well.
The main elements of the Mediterranean diet include:
*An abundance of plant foods, such as fruits, vegetables, cereals, nuts and beans.
*Using "good" fats, such as olive or canola oil, rather than butter or lard, and limiting dairy products like high-fat cheese and milk;.
*Eating moderate amounts of fish and poultry, rather than red meat.
*Finally, drinking a glass or two of red wine a day.
Many other factors besides diet, including the genes you inherit and advancing age, play an important role in who ultimately develops Alzheimer's. Still, the findings add to a growing body of evidence that a heart-healthy lifestyle, with plenty of exercise, a sound diet, not smoking, and keeping weight down, may help keep the brain young.
For more on ways to maintain your brain, visit www.ALZinfo.org.
Source: Nikolaos Scarmeas, M.D., Yaakov Stern, Ph.D., Richard Mayeux, M.D., et al: "Mediterranean Diet and Mild Cognitive Impairment." Archives of Neurology, Volume 66, Number 2, February 2009, pages 216-225.