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Title: Long-term dietary flavonoid intake and change in cognitive function in the Framingham Offspring cohort

Author
item SHISHTAR, ESRA - Tufts University
item ROGERS, GAIL - Jean Mayer Human Nutrition Research Center On Aging At Tufts University
item BLUMBERG, JEFFREY - Tufts University
item AU, RHODA - Boston University
item JACQUES, PAUL - Jean Mayer Human Nutrition Research Center On Aging At Tufts University

Submitted to: Public Health Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/28/2019
Publication Date: 2/24/2020
Citation: Shishtar, E., Rogers, G., Blumberg, J.B., Au, R., Jacques, P.F. 2020. Long-term dietary flavonoid intake and change in cognitive function in the Framingham Offspring cohort. Public Health Nutrition. 23(9):1576-1588. https://doi.org/10.1017/S136898001900394X.
DOI: https://doi.org/10.1017/S136898001900394X

Interpretive Summary: Age-related cognitive decline is regarded as one of the most important public health challenges in the U.S. because of the rapidly growing population of older adults. Identifying strategies for preventing, minimizing, and/or delaying cognitive decline would be highly valuable. There is limited evidence that certain dietary patterns including the Mediterranean-DASH Intervention for Neurodegenerative Delay (Mind), Mediterranean, and Dietary Approaches to Stop Hypertension (DASH) are associated with a slower age-related cognitive decline. These dietary patterns stress the importance of consuming plant-based foods such as fruits and vegetables. Bioactive components of these foods have also been widely explored for their potential neurocognitive benefits, particularly a group of phytonutrients called flavonoids. Findings from previous research have been conflicted, with some studies suggesting that flavonoids may be protective against cognitive decline and others suggesting no effect. We used data from the Framingham Heart Study to examine the association between dietary flavonoid intake and cognitive health. Specifically, we examined total flavonoids and sub-classes of flavonoids, including flavonols, flavanones, flavan-3-ols, flavones, flavonoid polymers, and anthocyanins. Participants completed food frequency questionnaires (FFQ) to capture dietary intake, as well as neuropsychological (NP) tests to assess cognitive health. Based on two repeated FFQ and three repeated NP testing assessments over a median follow-up of 11.5 years, our findings did not support an association between long-term higher flavonoid intakes and improved cognitive performance. In summary, the notion that flavonoids may exert long-term protective neurocognitive benefits remains unclear.

Technical Abstract: Objective: To examine the association between long-term total and the six classes of dietary flavonoid intake and decline in cognitive function over a follow-up period of up to 15 years. Design/Setting/Participants: Participants were from the Framingham Heart Study Offspring Cohort who were free of dementia, aged greater than or equal to 45 years, and had attended at least two of the last three clinical exams. Change in cognitive domain scores between two corresponding ancillary study exams represented an exam interval. Flavonoid intakes were assessed by a validated food frequency questionnaire at the start of each exam interval. Repeated-measures regression model was used to examine the longitudinal association between total and six flavonoid classes and annualized change in eight cognitive domains (verbal and visual memory, verbal learning, attention and concentration, abstract reasoning, language, visuoperceptual organization, and the global function). Results: Over a median follow-up of 11.5 years among 1874 participants, nominally significant trends toward a slower decline in cognitive function were only observed among those with higher flavonol (P 0.04), flavan-3-ol (P 0.06), and flavonoid polymer (P 0.02) intakes and visual memory. Nominal trends were also seen for flavonols in the following cognitive domains: global function, verbal learning, and visuoperceptual organization. Conclusion: In spite of modest nominal trends, overall our findings do not support a clear association between long-term high flavonoid intake and slowed age-related cognitive decline.