Mediterranean Diet and Age-Related Cognitive Decline: A Randomized Clinical Trial
(Valis-Pedret C et al, JAMA Intern Med 2015. 11.doi:10.1001/ jamainternmed.2015.1668. Epub ahead of print.)
As our patients age, they often worry about their memory and ask us if we can prescribe them something to either improve their memory or to prevent memory loss in the future. Unfortunately, we don’t have much to offer in terms of medications. Acetylcholinesterase inhibitors are somewhat helpful for those already diagnosed with dementia, but don’t seem to prevent cognitive decline. What about diet? Some observational studies have hinted that specific foods might protect against cognitive decline. This study was a randomized clinical trial conducted to determine if a Mediterranean diet (an antioxidant-rich cardioprotective dietary pattern) does indeed delay cognitive decline.
• 447 cognitively healthy men and women from Barcelona, Spain (mean age 66.9 years) were enrolled in this trial. They all had cardiovascular risk factors, but no actual heart disease (this was part of a larger study about the effects of diet on heart disease).
• They were randomly assigned to one of three intervention groups: a Mediterranean diet supplemented with extra virgin olive oil, a Mediterranean diet supplemented with mixed nuts, or a control diet (advised to reduce all dietary fat). Everyone had neuropsychological testing and Hamilton depression scale testing both at the beginning of the study and at the end. They were followed for a median of 4.1 years.
• A lot of participants dropped out of the study before getting their second neuropsych tests—113, or 25.3% of the group. Those who dropped out had somewhat lower MMSE scores, and were more likely to have the ApoE allele, a risk factor for dementia. This means that the results of the study are more likely to apply to elderly people who are sharper and who don’t have the ApoE allele.
• Participants assigned to the Mediterranean diet plus olive oil significantly outperformed those on the control diet in two of the three composite scores: frontal cognition and the global cognition. Those assigned to the Mediterranean diet plus nuts outperformed control on the memory composite score. Over the study period, 37 people developed mild cognitive impairment, with no significant difference among the different diets. The intervention had no effect on depression scores.
• The bad news: There were methodological problems with this study. (1) This was a post-hoc analysis of a subsample of data from a larger clinical trial. (2) There was substantial dropout rate, limiting the generalizability of the findings. (3) The subjects were not blinded to their treatments (eg, their diets). (4) The sample size was not big enough to be really confident in the findings.
• The good news: Nonetheless, the researchers did show that randomly assigning people to Mediterranean diets leads to measurable cognitive improvement relative to people asked simply to reduce dietary fat.
• Practice implications: Since the Mediterranean diets have been shown to improve heart health, and given these positive findings on cognitive functioning, go ahead and recommend this diet to your elderly patients. You can find more specifics about the diet from the National Center for Biotechnology
Information site: http://1.usa.gov/1PFcsw5.
Dr. James Megna is director of inpatient psychiatry and associate professor psychiatry and medicine at SUNY Upstate Medical University in Syracuse, NY.