Can cocoa help preserve memory in older adults?

By Lila Rouland | Published on December 9, 2025 | 3 min read


Aging is associated with an increased risk of cognitive decline and Alzheimer’s-related dementia. These disorders often begin with subtle impairments in cognitive functions long before clinical symptoms emerge. Early intervention to slow this progression represents a major public health challenge.

Cocoa flavanols, particularly (-)-epicatechin, are antioxidant and anti-inflammatory compounds believed to exert neuroprotective effects. Some epidemiological studies have reported an association between cocoa consumption and better cognitive performance. However, results from randomized clinical trials (RCTs) have been inconsistent, with limited long-term data and insufficiently detailed neuropsychological assessments.

What are the cognitive effects after two years of supplementation?

This investigation is part of the large COSMOS trial (21,442 participants), which included a clinic subcohort of 573 volunteers who underwent in-person neuropsychological testing at baseline and again after two years.

Participants (mean age 69.6 years) were randomly assigned to receive either cocoa extract or a placebo in a double-blind design. Cognitive testing assessed global cognition (a composite score based on 11 tasks), episodic memory, and executive function/attention.

After two years:

• No significant improvement was observed in the cocoa group compared with placebo, whether for global cognition (mean difference: -0.01 SD; 95% CI: -0.08 to 0.05), episodic memory (-0.01; CI: -0.13 to 0.10), or executive function (0.003; CI: -0.07 to 0.08).
• Both groups showed slight score increases, likely due to practice effects from repeated testing.
• Subgroup analyses suggested a potential benefit in participants with low baseline diet quality, who showed trends toward better global cognition and executive function.

Adherence to the intervention was high (>90% in both groups). No significant interactions were found by age, sex, medical history, or flavanol intake.

Does cocoa supplementation have clinical potential?

Cocoa, rich in flavanols and theobromine, exhibits vasodilatory, antioxidant, and anti-inflammatory properties. Theoretically, it may promote neurogenesis and cerebral perfusion, helping preserve cognitive function. However, this rigorous two-year study does not provide evidence of an overall cognitive benefit in healthy older adults.

Limitations include low ethnic diversity, a follow-up period too short to detect early effects, and a lack of correction for multiple secondary analyses. The dose used (500 mg/day) may also have been insufficient for certain at-risk individuals.

Nonetheless, the positive signal observed among participants with poor diet quality highlights an important avenue for future research. Cognitive benefits may vary according to baseline nutritional status, underscoring the need for stratified approaches in upcoming trials.  

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