Adhering to a Mediterranean diet appears to lower the risk of progressing from mild cognitive impairment to Alzheimer's disease and may cut the risk of developing MCI as well, according to a recent study.
There may also be a dose-response effect, with greater adherence to the Mediterranean diet conferring greater protection from cognitive decline, said Dr. Nikoloaos Scarmeas and his associates at Columbia University Medical Center, New York.
The researchers assessed the association between diet and MCI and AD using data from the Washington Heights-Inwood Columbia Aging Project.
The WHICAP study included comprehensive neuropsychological testing of probability samplings of Medicare beneficiaries residing in Manhattan in 1992 and 1999.
A total of 1,800 subjects who were cognitively normal at baseline were followed for approximately 4 years for the development of MCI. The investigators also followed 564 patients with MCI at baseline for the progression to AD (Arch. Neurol. 2009;66:216–25).
The Mediterranean diet is characterized by high intake of fish, vegetables, legumes, fruits, cereals, and unsaturated fatty acids, mostly in the form of olive oil; low intake of dairy products, meat, and saturated fatty acids; and regular but moderate intake of alcohol.
Greater adherence to this type of diet was associated with “a borderline trend for lower risk of developing MCI,” Dr. Scarmeas and his associates said. Compared with subjects who did not adhere to the Mediterranean diet, those who reported intermediate adherence had a 17% lower risk of developing MCI; those who reported greatest adherence had a 28% lower risk.
Greater adherence to the Mediterranean diet also was associated with a lower risk of progressing to AD.
Compared with subjects who did not adhere to this type of diet, those who reported intermediate adherence had a 45% lower risk of progressing to AD; those who reported greatest adherence had a 48% lower risk, the investigators said.
The findings did not change when the data were adjusted to account for several potential confounders such as subject age, gender, ethnicity, level of education, apolipoprotein E genotype, caloric intake, and body mass index.
The investigators received support for the study through grants from the National Institute on Aging.