There are many studies that indicate that following a Mediterranean diet lowers total cholesterol levels, blood sugar and decreases the risk of cardiovascular disease and type 2 diabetes. There are also now studies that show a decrease in the risk of Alzheimer's disease (AD).
From Medscape News (January 6, 2011):
"Older adults who stick close to a traditional Mediterranean diet (MedDiet) experience slower rates of cognitive decline as they age, new research suggests.
"Our findings from this prospective cohort suggest that adherence to a Mediterranean diet is not only a heart healthy diet plan but also one that fosters a healthier functioning brain,” Christine C. Tangney, of the Department of Clinical Nutrition, Rush University Medical Center, Chicago, Illinois, told Medscape Medical News.
Their results were published online December 22, 2010, in the American Journal of Clinical Nutrition."
Following a low-saturated-fat, low-glycemic-index diet has actually been found to decrease levels of β-amyloid 42, a measurable biomarker of Alzheimer's disease risk.
Genetics and Alzheimer's Disease
One genetic risk factor does appear to increase a person’s risk of developing AD. This increased risk is related to the apolipoprotein E (APOE) gene found on chromosome 19. APOE contains the instructions needed to make a protein that helps carry cholesterol in the bloodstream. APOE comes in several different forms. Three forms—APOE ε2, APOE ε3, and APOE ε4—occur most frequently. Diet should be a particular concern for those people that carry the APOE ε4 gene. Dozens of studies have confirmed that the APOE ε4 allele increases the risk of developing AD, but how that happens is not yet completely understood. These studies also have helped explain some of the variation in the age at which AD develops, as people who inherit one or two APOE ε4 alleles tend to develop AD at an earlier age than those who do not have any. APOE ε4 is called a risk-factor gene because it increases a person’s risk of developing AD. However, inheriting an APOE ε4 allele does not mean that a person will definitely develop AD. Some people with one or two APOE ε4 alleles never get the disease, and others who develop AD do not have any APOE ε4 alleles.
Certainly if one has a close relative that has developed AD, testing for the APOE gene should be considered and following a low-saturated-fat, low-glycemic-index Mediterranean style diet would be even more important for those carrying the APOE ε4 gene. Testing for this risk factor can be done at our office. We also offer a program specifically designed for those carrying this gene to lower their risk of developing AD and cardiovascular disease and diabetes.