Mediterranean diet and brain volume

I sent out a recent blog on a Spanish intervention trial of a Mediterranean Diet, which was associated with a decrease in breast cancer risk. This same study (the PREDIMED study) also found decrease likelihood of developing atrial fibrillation, coronary artery disease, diabetes and improved cognition (see prior blogs: http://gmodestmedblogs.blogspot.com/2014/05/olive-oil-and-atrial-fibrillation.html , http://gmodestmedblogs.blogspot.com/2014/01/mediterranean-diet-and-primary.html , http://gmodestmedblogs.blogspot.com/2014/01/mediterranean-diet-diabetes-prevention.html  ). The PREDIMED substudy on cognitive decline looked at 522 participants at high vascular risk, randomized them to 2 Mediterranean diets (one high in extra-virgin olive oil and the other high in nuts) vs a low-fat control. they tracked participants with the Mini-Mental State Exam (MMSE) and Clock Drawing Test for 6.5 years and found that, controlling for apo E genotype, family history of cognitive impairment/dementia, depression and the array of cardiovascular risk factors, participants in either of the Mediterranean diets did better (though those on the high extra-virgin olive oil did a little better than the high nut one) --see cognitive function better with Mediterr diet JNeurol2013 in dropbox, or J Neurol Neurosurg Psychiatry 2013;84:1318–1325.  

There was a recent study which looked at Mediterranean diet and brain structure. Patients were in the Washington Heights-Inwood Columbia Aging Project (WHICAP), following 2,258 community-dwelling non-cognitively impaired individuals in New York and prospectively evaluating them for Alzheimer's Disease every 1.5 years. They found 262 incident cases of Alzheimer's over 4 years, and found an overall 9% decreased risk of Alzheimer's with greater adherence to a Mediterranean diet, with a 40% decreased risk in comparing the highest to the lowest tertile of consuming a Mediterranean diet, in a multivariate analysis controlling for the usual suspects (see Mediterranean diet and risk Alz AnnNeuro2006 in dropbox, or Ann Neurol 2006;59:912–921​). These results have been confirmed in several observational studies, but not all.

in the current study, researchers looked at adherence to a Mediterranean diet and several MRI-determined variables of brain architecture (see Mediterranean diet and brain structure. neurol2015 in dropbox, or  doi.10.1212/WNL.0000000000002121). They scored adherence to the Mediterranean diet from 0-9. details:

--674 subjects of whom 370 had lower adherence to Med diet (score 0-4) and 304 with higher adherence (score 5-9)

--mean age 80.1, 10.7 years of education, 67% female, 25% apo e-4 positive, 28% white/35% black/36% Hispanic, BMI 27.8, 21% with diabetes, 74% hypertension, 10.5% stroke.

--results:

    ​--those with higher total brain volume were younger, had higher education, more often male, less likely to have diabetes, and had lower BMI.

    --those with higher Med diet adherence (5-9) vs lower (0-4) had:

        --higher total brain volume by 13.11 ml (p=0.007) 

 --higher total gray matter volume by 5.00 ml (p=0.05)
 --higher total white matter volume by 6.41 ml (p=0.05)

       --specific components of the Mediterranean Diet:

            --higher fish consumption and lower meat consumption were associated with higher total gray matter volume

            --lower meat intake was associated with larger total brain volume

            --higher fish intake was associated with a 0.019 mm larger mean cortical thickness (p=0.03)

            --volumes of the cingulate cortex, parietal lobe, temporal lobe, and hippocampus, and cortical thickness of the superior-frontal region were associated with dietary factors, esp higher fish and lower meat intakes

    --overall, Med Diet adherence was associated with less brain atrophy, equivalent to the effects of 5 years of aging, with higher fish and lower meat intakes being the most significant association.

So, this is yet another study confirming the benefits of eating well. The constellation of findings, whether related to developing diabetes, heart afflictions, or cognitive decline, reinforce that diet is important for the whole body, and that in some ways our reductionist approach (looking just at coronary artery disease, for example) can lead to the wrong conclusions (just put people on statins and aspirin and don’t worry). So, I bring up this study mostly to reinforce overall the benefits of healthy lifestyle and that it probably is one of the most important messages we in primary care can impart on our patients. Of course, some of these suggestions are structurally difficult in our society (eating well requires access to affordable healthy foods, exercise requires access to safe neighborhoods in which to walk, etc), but, at least in Boston, there are lots of grassroots initiatives to improve access to food and safe neighborhoods, from which my patients have benefited significantly. [And it would be great to generalize/develop access to good foods and safe neighborhoods more broadly…..]