The effects of the Multicultural Healthy Diet on cognitive decline and Alzheimer's disease risk: a phase II randomized controlled trial in middle-aged adults

Background: Anti-inflammatory dietary patterns are associated with slower cognitive decline in older adults; however, little is known about the effects of an anti-inflammatory dietary pattern in middle age. Objectives: This study aims to adapt an anti-inflammatory diet to a multicultural setting and assess its impact on cognitive decline and Alzheimer's disease risk and related dementias in healthy middle-aged adults. Methods: We performed a phase II pilot randomized clinical trial in adults (40–65 y old; n = 290) in Bronx, New York. Participants were assigned to follow either the Multicultural Healthy Diet (MHD), an anti-inflammatory diet, or usual diet (Comparison). Diet was evaluated using the National Cancer Institute's Automated Self-Administered 24-h food records. The primary cognitive outcome was assessed at 9 mo after randomization using a global composite score derived from 3 ambulatory cognitive assessments of visuospatial memory (Grid Memory), processing speed (Symbol Search) and short-term associative memory binding (Color Shapes). Secondary outcomes included performance on individual tests and association of dietary components with cognitive performance. Results: At 9-mo follow-up, the MHD arm had a lower Dietary Inflammatory Index (DII) score based on self-reported diet, with an adjusted MHD minus Comparison difference of –0.64 [95% confidence interval (CI): –1.02, –0.27] and –0.94 (95% CI: –1.34, –0.54) for the DII and energy-adjusted DII scores, respectively, indicating intervention participants had adhered to an anti-inflammatory dietary pattern. Group session and telephone contact completion averaged 93% and 72%, respectively, for the MHD arm. No statistically significant difference between arms was found in the primary outcome—cognitive global score change—from baseline: –0.06 (95% CI: –0.15, 0.04), P = .259. Conclusions: The MHD is feasible and acceptable in this multicultural United States cohort. Although the influence of MHD at 9 mo is nonsignificant based on the global composite cognitive score, additional research using other measures such as day-to-day variability in cognitive function and peak performance is warranted. This study was registered at clinicaltrials.gov as NCT03240406 (https://clinicaltrials.gov/study/NCT03240406?term=Diet%20%26%20Cognition&page=3&rank=30).