RESUMO
INTRODUCTION: We assessed the effects of multivitamin-mineral and cocoa extract supplementation on incident mild cognitive impairment (MCI) and all-cause probable dementia. METHODS: COSMOS-Mind (N = 2262), a 2 × 2 factorial, randomized-controlled clinical trial administered a telephone-based cognitive battery at baseline and annually for 3 years. Incidence rates of MCI, and separately dementia, were compared among treatment arms with proportional hazards regression. RESULTS: Over 3 years, 110 incident MCI and 14 incident dementia cases were adjudicated. Incidence rates did not vary by assignment to multivitamin-mineral or cocoa extract (all p's ≥ 0.05); however, statistical power was low. When participants assigned to multivitamin-mineral versus placebo converted to MCI, their scores for global cognition (p = 0.03) and executive function (p < 0.001) were higher and had declined less relative to the previous year (p = 0.03 for global cognition; p = 0.004 for executive function). DISCUSSION: Multivitamin-mineral therapy may provide cognitive resilience, countering conversion to MCI, but not significantly reduce its incidence over 3 years. HIGHLIGHTS: Multivitamin-mineral supplementation did not reduce risks for cognitive impairment. Cocoa extract supplementation did not reduce risks for cognitive impairment. Multivitamin-mineral supplementation slowed cognitive declines for incident mild cognitive impairment.