Mediterranean Diet and Alzheimer's Disease Prevention

There is an urgent need to identify strategies to prevent or delay the onset of Alzheimer's disease and other forms of dementia.

The role of diet as a prevention strategy is controversial. Some research evidence supports a role for a Mediterranean diet in cognitive health and dementia prevention.

A recent brain imaging study adds to this evidence. Dr. Lisa Mosconi and colleagues at New York University School of Medicine completed a cross-sectional study of brain magnetic resonance imaging and diet was completed in 52 older cognitively normal individuals.

The key elements of the design of this study were:

• Subjects: Community subjects participating in a longitudinal brain imaging study with a mean age of 54 years (standard deviation 12 years). Approximately 2/3 of the subjects were women.
• Study measures: Dietary information was collected using the Harvard/Willet food frequency questionnaire and subjects were rated on adherence to a Mediterranean diet using the MeDi. This scale rates intake of fruit, vegetables, legumes, cereal and fish as beneficial with dairy and meat intake rated detrimental. Information on dietary fat and alcohol were also used rated for a nine-item Mediterranean diet score. Subjects scoring greater than 5 were rated as Mediterranean diet adherent. 
• Brain imaging: All subjects completed a cross-sectional brain MRI using a 1.5 Tesla scanner. Volumetric brain measures were calculated using FreeSurfer software.
• Statistical analysis: Multivariate general linear modeling was used to assess the correlation of diet (high vs low Mediterranean diet adherence) with correction for a variety of potential confounding variables including age, gender, family history of Alzheimer's disease, APOE gene status and BMI.

The brain analysis focused on regions of the brain known to show atrophy with Alzheimer's dementia. 

This analysis showed Mediterranean diet adherent subjects with statistically significant greater brain thickness measures in the left brain hemisphere for:

• entorhinal cortex
• orbitofrontal cortex
• posterior cingulate cortex

This effect was found in the uncorrected volumetric data and the relationship remained with correction for age and total intracranial volume measures.

The authors note previous brain imaging studies have linked cognitive decline and dementia with atrophy of the left hemisphere regions of the brain found significantly linked to Mediterranean diet adherence in this study.

An additional brain area of atrophy in Alzheimer's is the hippocampus a region not addressed in the current research study.

The take home message here is that this study:

"provides support for further exploration of dietary behavior as a possible AD (Alzheimer's disease) prevention strategy".

The sample size is this study is relatively small and will need replication in other larger sample sizes. 

There was no correlation with neuropsychological scores and Mediterranean diet in this study. This is not surprising as the subjects were recruited as being cognitively normal.

It will be interesting to see in the longitudinal follow up if Mediterranean Diet adherence relates to neuropsychological performance and brain atrophy over time.

Readers with more interest in this research can find the free full-text manuscript by clicking on the PMID link in the citation below.

Photo of macaw is from the author's files.

Follow the author on Twitter @WRY999.

Mosconi L, Murray J, Tsui WH, Li Y, Davies M, Williams S, Pirraglia E, Spector N, Osorio RS, Glodzik L, McHugh P, & de Leon MJ (2014). Mediterranean Diet and Magnetic Resonance Imaging-Assessed Brain Atrophy in Cognitively Normal Individuals at Risk for Alzheimer's Disease. The journal of prevention of Alzheimer's disease, 1 (1), 23-32 PMID: 25237654