The goal of the COSMOS Web study is to determine whether a dietary intervention with flavanol-containing cocoa extract has an effect on cognitive function in older adults (age 60+). The study will be conducted in a subset of 4000 participants from the COSMOS study (NCT02422745). The investigators' recent work (Sloan et al., submitted) showed that cocoa flavanol consumption over 12 weeks led to improvements in immediate recall on the ModRey verbal memory task in healthy older adults.

In COSMOS Web, the investigators are testing the effect of a dietary intervention with flavanol-containing cocoa extract on a range of aging-related cognitive measures, as assessed through a novel online-administered test battery, in a cohort of older participants. Change in ModRey (Modified Rey Auditory Verbal Learning Test) immediate recall performance over 1 year of cocoa extract consumption will be our primary outcome measure. Secondary endpoints will include change in ModRey performance at 2- and 3-year follow-up, and change in performance tests of a novel object recognition task, executive function/working memory, and spatial memory at 1-, 2-, and 3- years follow-up. This study will explore whether baseline measures of cognition and nutritional status can predict differential effects of the cocoa extract supplementation. This study will also explore the effect of multivitamin intake on the primary and secondary outcomes noted above and test whether multivitamin intake interacts with flavanol intake from cocoa extract to enhance or mitigate effects on cognitive outcomes. In a subset of participants evaluated in person, this study will examine the impact of cocoa extract intake and explore the main and interacting effects of multivitamins on cognitive changes and brain structure and function appreciated with magnetic resonance imaging over a 2-year period.

Leveraging the COSMOS study, which has randomized 21,442 older adult participants into cocoa extract and placebo interventions, the study team at Brigham and Women's Hospital, who administer the parent COSMOS trial, are recruiting \~4000 older adult volunteers to participate in COSMOS Web (this study) an online cognitive testing battery developed by the team at Columbia University. These 4000 participants will complete an initial online cognitive assessment and additional assessments after one, two, and three years of follow-up. In addition, approximately 200 COSMOS Web participants who live in the Boston area will complete clinic-based study visits at the Clinical and Translational Science Center at Brigham and Women's Hospital. During that visit, they will complete a neuropsychological test battery, for comparison to their performance online. This study will examine the impact of dietary interventions with cocoa extract and explore the main and interacting effects of multivitamin intake on cognitive changes and brain structure and function appreciated with magnetic resonance imaging over a 2-year period.

After the COSMOS trial began, an advanced method to analyze cocoa flavanols was accredited by AOAC International as a First Action Official Method of Analysis (https://doi.org/10.1093/jaoacint/qsaa132). This updated method relies on a reference material (RM8403) recently standardized and made commercially available by the U.S. National Institute of Standards and Technology. While the actual cocoa flavanol content of the COSMOS intervention remained unchanged throughout the trial, the application of this new analytical method led to expected changes in how the total cocoa flavanol content is now reported. Applying AOAC 2020.05/RM8403 to the COSMOS intervention, the total cocoa flavanol content of the COSMOS intervention is now 500 mg/day. Reporting of (-)-epicatechin content remained unaffected. Going forward, we will therefore apply AOAC 2020.05/RM8403 and report that the COSMOS intervention tested 500 mg/day of cocoa flavanols, including 80 mg of (-)-epicatechin.