Nutrient Patterns Tied to Brain Volume, Cognitive Function

Megan Brooks

December 29, 2011

December 29, 2011 — A study of relatively healthy elderly adults found that those with diets rich in several vitamins or omega-3 fatty acids had better cognitive function and less brain atrophy associated with Alzheimer's disease than their peers with diets less abundant in these nutrients.

The study identified 3 distinct nutrient biomarker patterns (NBPs) in blood that are related to cognitive performance and magnetic resonance imaging (MRI) measures of brain aging.

Two NBPs were associated with more favorable cognitive scores and more total brain volume on MRI. One was high in plasma B vitamins (B1, B2, B6, folate, and B12), as well as vitamins C, D, and E, and the other was high in plasma marine omega-3 fatty acids.

A third NBP characterized by a high trans fat pattern was consistently associated with less favorable cognitive function and less total cerebral brain volume.

The study was published online December 28 in Neurology.

The Oregon Brain Aging Study

First author Gene Bowman, ND, MPH, from the Oregon Health & Science University, Portland, and colleagues studied a cross-sectional sample of 104 elderly adults (62% women; mean age, 87 years) participating in the Oregon Brain Aging Study.

Comorbidities and vascular risk factors for cognitive decline were low in the cohort, with the exception of hypertension, which was present in 44% of the participants. The mean Mini-Mental State Examination was 27, and no patient had a Clinical Dementia Rating higher than 0.5.

All of the participants completed a battery of neuropsychological tests of memory and thinking skills. A subset of 42 patients underwent MRI scans to measure brain volume. Fasting plasma samples were used to determine the levels of various nutrients present in blood. "To our knowledge, this is the first study to apply principal component analysis to biological markers of diet," the researchers note.

Overall, the participants had good nutritional status, although 7% were deficient in vitamin B12 (<200 pg/mL) and 25% were deficient in vitamin D (<20 ng/mL).

The investigators looked at 30 different nutrient biomarkers. They report that the NBP characterized by higher vitamin BCDE levels was associated with better global cognitive function, particularly in domains of executive, attention, and visuospatial function.

Conversely, the NBP characterized by higher plasma trans fat scores was associated with worse cognitive function overall (memory, attention, language, processing speed, and global).

The researchers report that each standard deviation (SD) increase in the vitamin BCDE score was associated with a 0.28 SD increase in global cognitive score, and each 1 SD increase in the trans fat score was associated with a 0.30 SD decrease in global cognitive score.

Patients with an NBP characterized by higher marine omega-3 fatty acid levels had better executive function.

Adjustment for age, sex, education, apolipoprotein E4, hypertension, and depression did not attenuate these relationships, the authors write.

Blood Nutrient Patterns Affect MRI Patterns

On brain MRI, the researchers found that patients with higher plasma BCDE scores had more total cerebral brain volume, and those with higher trans fat scores had less total cerebral brain volume.

Those with higher omega-3 scores had less white matter hyperintensities, but this relationship was attenuated after adjusting for depression and hypertension.

In an exploratory analysis, the researchers found that NBPs accounted for a significant amount of variation in both brain volume and cognitive scores. Age, sex, education years, APOE4 carrier status, depression, and hypertension together explained 46% of the variation in the global cognitive z score, and adding the NBPs explained an additional 17%.

In regard to total brain volume on MRI, the covariates explained 40% of the total variation, and the NBPs explained an additional 37% of the variation. The covariates explained 52% of the variation in white matter hyperintensities, and the NBPs explained an additional 9%.

Dr. Bowman and colleagues say additional studies in different populations are needed to confirm these findings.

Patterns Predictive of Cognitive Change

The coauthors of a linked commentary say, "If the relationships between cognitive scores and MRI measures with [NBPs] are confirmed in a larger, more ethnically diverse sample of older adults, this approach should be exploited to extract [NBPs] predictive of cognitive change.

"Moreover, additional biomarkers for food group and food subgroups might be explored — i.e., reservatrol for wine, hydroxytyrosol for olive oil and nuts, or proline betaine for citrus fruits," suggest commentators Christy C. Tangney, PhD, from Rush University Medical Center, Chicago, Illinois, and Nikolaos Scarmeas, MD, from Columbia University, New York City.

A strength of the study, they say, is the investigators' use of plasma nutrient levels, rather than self-reported dietary patterns, which gets around recall errors and biases that can occur when individuals report their usual diets, particularly in elders who may be cognitively challenged.

Potential limitations of this bioassay strategy for estimating diet is cost and a higher patient burden, they add, such as time and fasting, if necessary.

The study was supported by the National Institutes of Health, the National Institute on Aging, the National Center for Complementary and Alternative Medicine, and the US Department of Veterans Affairs, Portland VA Medical Center. A complete list of author disclosures can be found with the original articles.

Neurology. Published online December 28, 2011. Article abstract, Commentary


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