Food choices and their consequences may certainly affect cognitive function. A new study led by investigators at Brigham and Women’s Hospital, a founding member of Mass Brigham Healthcare System, along with external collaborators, expands on previously published work (focusing on Puerto Rican individuals in the United States) by including additional races and ethnicities. The team found that some plasma metabolites-; Substances that arise when the body breaks down food-; They were associated with global cognitive function scores across a variety of races and ethnicities. Their results were published in Alzheimer’s and Dementia: Journal of the Alzheimer’s Association.
Our study has tremendous strengths in expanding sample size and adding demographics compared to what previous research has done. It also shows that studies that begin with a focus on minorities can lead to insights that may be useful to other populations. We hope our findings will help people make specific dietary choices and improve their cognitive health.”
Tamar Sofer, PhD, is director of the Biostatistics Core Program in Sleep Epidemiology and a member of Brigham’s Division of Sleep Disorders and Everyday Day.
Nowadays, researchers can detect biomarkers associated with health changes and disease by using approaches such as metabolic profiling, which can scan thousands of metabolites within blood samples. A preliminary study in Boston looking at elderly Puerto Ricans found a series of metabolites that were associated with measured cognitive functions. Building on this work, Brigham researchers tested associations of cognitive metabolic functions in 2,222 Hispanic/Latino American adults from the Hispanic Community Health Study/Study (HCHS/SOL), and in 1,365 Europeans and 478 African Americans from atherosclerosis risk in communities ( ARIC) study. They then applied Mendelian Randomization (MR) analyzes to identify causal associations between metabolites and cognitive function, as well as between the Mediterranean diet and cognitive function.
The team discovered that six metabolites were consistently associated with lower global cognitive function across all studies. Four of them were sugars or derivatives of sugars. Another metabolite, beta-cryptoxanthin, is associated with higher global cognitive function in HCHS/SOL, and is also closely associated with fruit consumption.
“It is likely that these metabolites are biomarkers of a more direct relationship between diet and cognitive function,” said lead author Inat Granot Hershkowitz, PhD, who worked on the study as a postdoctoral fellow in the Soffer Laboratory in Brigham.
The diet itself can be an important source of many metabolites, including some that have positive or negative associations with cognitive function. In this study, a 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 levels of other metabolites, which were associated with reduced cognitive function. Previous research has also shown that adherence to the Mediterranean diet is associated with cognitive benefits.
While the study had limitations such as its cross-sectional censorship design that limited conclusions about the potential effect of modulating metabolic levels on cognitive function (causal inference), the researchers attempted to use MR analyzes to explain unmeasured confusion 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 evaluate the metabolite’s associations with cognitive function and work to assess whether the associations observed actually indicate that changes in diet – shown in altered levels of metabolism – 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,” Sofer said. “Our study further supports the importance of a healthy diet towards protecting cognitive function, consistent with race and ethnicity.”