Low Levels of a Urinary Biomarker of Dietary Polyphenol Are Associated with Substantial Cognitive Decline over a 3-Year Period in Older Adults: The Invecchiare in Chianti Study

OBJECTIVES: To investigate the association between total urinary polyphenols (TUPs) and total dietary polyphenols (TDPs) and cognitive decline in an older population. DESIGN: The Invecchiare in Chianti (InCHIANTI) study, a cohort study with 3 years of follow-up. SETTING: Tuscany, Italy. PARTICIPANTS: Individuals without dementia aged 65 and older (N = 652). MEASUREMENTS: TUP and TDP concentrations were analyzed at baseline using the Folin-Ciocalteu assay and a validated food frequency questionnaire, respectively. Cognition was assessed using the Mini-Mental State Examination (MMSE) and Trail-Making Test (TMT) at baseline and after 3 years of follow-up. Substantial cognitive decline was defined as a reduction in MMSE score of three or more points and an increase of at least 29 seconds on the TMT Part A (TMT-A) and 68 seconds on the TMT Part B (TMT-B) (the worst 10% of the distribution of decline) or as test discontinued because of multiple mistakes on the TMT A and B at follow-up. RESULTS: Higher TUP levels were associated with lower risk of substantial cognitive decline on the MMSE (odds ratio (OR) comparing extreme tertiles = 0.53, 95% confidence interval (CI) = 0.34-0.85, P-trend = .008) and on the TMT-A (OR = 0.52, 95% CI = 0.28-0.96, P-trend = .03), but not on TMT-B in a logistic regression model that adjusted for baseline cognitive score and potential confounding factors. TDP did not affect the development of substantial cognitive decline in either test. CONCLUSION: High concentrations of polyphenols, a nutritional biomarker of polyphenol intake, were associated with lower risk of substantial cognitive decline in an older population studied over a 3-year period, suggesting a protective effect against cognitive impairment.