Mild Cognitive Impairment (MCI) is considered a precursor to dementia, although it does not always lead to dementia.
A study published in 2009 in the Archives of Neurology indicates that adherence to the Mediterranean diet reduces both the risk of developing MCI and the risk of MCI conversion to Alzheimer dementia.
1,393 residents of a multi-ethnic community in New York were enrolled in the study. They were mentally normal at baseline and followed for an average of 4.5 years.
Another 482 residents were identified as having Mild Cognitive Impairment at baseline, and were followed an average of 4.3 years.
All participants were screened for cognitive impairments and surveyed to get an idea of usual food intake. Researchers used a 10-point scale to describe an individual participant’s adherence to the Mediterranean diet. The higher the score, the greater the participant’s adherence. Participants were then divided into thirds (tertiles) based on whether adherence was low, medium, or high. Average age of study subjects on entry was 77.
275 of the 1,393 participants who were mentally normal at baseline developed Mild Cognitive Impairment over the 4.5 years of follow-up. Compared to those participants in the lowest third of Mediterranean diet adherence, those in the middle third had 17% less risk of developing MCI, and those in the highest third had 28% less risk.
Of 482 participants with Mild Cognitive Impairment at baseline, 106 later developed Alzheimer disease. Compared with participants in the lowest third of adherence, those in the middle third had 45% less risk of developing Alzheimer disease, and those in the highest third had 48% less risk.
Comments From the Study Authors
. . . potentially beneficial effects for mild cognitive impairment or mild cognitive impairment conversion to Alzheimer’s disease have been reported for alcohol, fish, polyunsaturated fatty acids (also for age-related cognitive decline) and lower levels of saturated fatty acids.
The Mediterranean diet tends to improve cholesterol levels, overall blood vessel function, reduce inflammation, and lower blood sugar levels, all of which could help preserve brain function.
No surprise here.
The traditional Mediterranean diet has long been associated with lower risk of developing dementia, both Alzheimer and vascular dementia. Vascular dementia results from multiple strokes or poor blood flow to the brain. Since Mild Cognitive Impairment precedes Alzheimer dementia, it makes sense that the Mediterranean diet could help prevent both.
The lead author of the study at hand, Dr. Scarmeas, also reported in 2007 that the Mediterranean diet also prolongs life in established Alzheimer patients.
Reference: Scarmeas, Nikolaos, et al. Mediterranean Diet and Mild Cognitive Impairment. Archives of Neurology, 66 (2009): 216-225.
Additional Resource: Oldways’ Mediterranean diet information