Diet might play role in cognitive function across diverse races, ethnicities: Study

A new research headed by Brigham and Women’s Hospital, a founding member of the Mass General Brigham healthcare system, and outside colleagues builds on previously published work by integrating more races and ethnicities.

The researchers discovered that particular plasma metabolites—substances produced by the body when it digests food—were linked to global cognitive function scores across a wide range of races and ethnicities. Their findings were published in Alzheimer’s & Dementia: The Alzheimer’s Association Journal.

“Our study has huge strengths in expanding the sample size and in adding demographics compared to what previous research has done,” said Tamar Sofer, Ph.D., and director of the Biostatistics Core Program in Sleep Medicine Epidemiology and a member of the Division of Sleep and Circadian Disorders at the Brigham.

Tamar added, “It also illustrates that studies that begin by focusing on minorities can give rise to insights that may be beneficial to other populations. We hope our findings will help people in making specific nutritional choices and in improving their cognitive health.”

Researchers may now find biomarkers linked to health changes and illnesses using techniques such as metabolomic profiling, which can assess hundreds of compounds in blood samples. An first investigation in Boston of elderly persons of Puerto Rican heritage discovered a variety of metabolites linked to evaluated cognitive abilities.

Researchers may now find biomarkers linked to health changes and illnesses using techniques such as metabolomic profiling, which can assess hundreds of compounds in blood samples. An first investigation in Boston of elderly persons of Puerto Rican heritage discovered a variety of metabolites linked to evaluated cognitive abilities.

Building off that work, Brigham researchers tested metabolite-cognitive function associations in 2,222 U.S. Hispanic/Latinx adults from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL), and in 1,365 Europeans and 478 African Americans from the Atherosclerosis Risk In Communities (ARIC) Study. They then applied Mendelian Randomization (MR) analyses to determine causal associations between the metabolites and cognitive function, as well as between a Mediterranean diet and cognitive function.

The team discovered that six metabolites were consistently associated with a lower global cognitive function across all of the studies. Four of them were sugars or derivatives of sugars. Another metabolite, beta-cryptoxanthin, was associated with a higher global cognitive function in the HCHS/SOL and is also strongly correlated with fruit consumption.

“It is possible that these metabolites are biomarkers of a more direct relationship between diet and cognitive function,” said lead author Einat Granot-Hershkovitz, Ph.D., who worked on this study as a postdoctoral fellow in Sofer’s lab at Brigham.

Diet itself can be an important source of many metabolites, including some with positive or negative associations with cognitive function. In this study, the Mediterranean diet score was associated with higher levels of beta-cryptoxanthin, which was positively associated with cognitive function. The Mediterranean diet was also negatively associated with the levels of other metabolites, which were associated with lower cognitive function. Previous research has also shown that adherence to the Mediterranean diet is associated with cognitive benefits.

While the study did have limitations like its cross-sectional, observational design which limited conclusions about the potential influence of modifying metabolite levels on cognitive function (causal inference), the researchers attempted to use MR analyses to account for unmeasured confounding and establish some level of causal inference. Their results showed weak causal effects between specific metabolites and global cognitive function.

The researchers recommend that future studies assess metabolite associations with cognitive function and work to evaluate whether observed associations indeed indicate that changes in diet – manifesting in changing metabolite levels – can improve cognitive health.

“While the causal effect seen in our study may be weak, repeated research has shown that the Mediterranean diet is associated with better health outcomes, including cognitive health,” said Sofer. “Our study further supports the importance of a healthy diet towards safeguarding cognitive function, consistent across races and ethnicities.”

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