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Dietary flavanols restore hippocampal-dependent memory in older adults with lower diet quality and lower habitual flavanol consumption.
Brickman, AM, Yeung, LK, Alschuler, DM, Ottaviani, JI, Kuhnle, GGC, Sloan, RP, Luttmann-Gibson, H, Copeland, T, Schroeter, H, Sesso, HD, et al
Proceedings of the National Academy of Sciences of the United States of America. 2023;120(23):e2216932120
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Plain language summary
“Cognitive aging” is a term used to describe how some of our cognitive abilities decline during the aging process, independent of late-life cognitive diseases. Because cognitive aging is meaningfully disruptive to our lives, it is biomedically justified to identify its etiologic factors. The current study was ancillary to COSMOS and termed COSMOS-Web. COSMOS was designed to examine the effects of cocoa extract and multivitamin supplementation on total cardiovascular disease and total invasive cancer. For this study, the focus is on the cocoa extract intervention only. Participants were randomly assigned to a 3-year intervention of cocoa extract or a placebo. Results showed that a flavanol intervention-based restoration of memory was observed in the lower tertile of habitual diet quality and in the subset of participants with lower habitual flavanol consumption. The improvement in memory was apparent after 12 months of intervention and appeared to be sustained over the 3 years of follow-up. Additionally, diet quality is a key lifestyle factor linked to the hippocampal and not to the prefrontal component of cognitive aging. Authors concluded that habitual flavanol consumption and diet quality at baseline are positively and selectively correlated with hippocampal-dependent memory. Improvements in the flavanol biomarker over the trial were associated with improving memory.
Abstract
Dietary flavanols are food constituents found in certain fruits and vegetables that have been linked to cognitive aging. Previous studies suggested that consumption of dietary flavanols might specifically be associated with the hippocampal-dependent memory component of cognitive aging and that memory benefits of a flavanol intervention might depend on habitual diet quality. Here, we tested these hypotheses in the context of a large-scale study of 3,562 older adults, who were randomly assigned to a 3-y intervention of cocoa extract (500 mg of cocoa flavanols per day) or a placebo [(COcoa Supplement and Multivitamin Outcomes Study) COSMOS-Web, NCT04582617]. Using the alternative Healthy Eating Index in all participants and a urine-based biomarker of flavanol intake in a subset of participants [n = 1,361], we show that habitual flavanol consumption and diet quality at baseline are positively and selectively correlated with hippocampal-dependent memory. While the prespecified primary end point testing for an intervention-related improvement in memory in all participants after 1 y was not statistically significant, the flavanol intervention restored memory among participants in lower tertiles of habitual diet quality or habitual flavanol consumption. Increases in the flavanol biomarker over the course of the trial were associated with improving memory. Collectively, our results allow dietary flavanols to be considered in the context of a depletion-repletion paradigm and suggest that low flavanol consumption can act as a driver of the hippocampal-dependent component of cognitive aging.