High-dose DHA reaches the brain but fails to protect memory

High-dose DHA successfully reached the brains of older adults at increased risk of Alzheimer's disease, but the two-year clinical trial found no improvements in memory or brain structure, challenging assumptions that greater omega-3 delivery alone can slow cognitive decline.

Study: CNS target engagement of high-dose DHA supplementation in older adults at risk for dementia: a randomised, double-blind, placebo-controlled trial. Image credit: PeopleImages/Shutterstock.com

A clinical trial published in eBioMedicine found that high-dose docosahexaenoic acid (DHA) supplementation successfully increased brain DHA levels in older adults at risk of dementia, including those carrying the APOE ε4 Alzheimer's risk variant. However, despite reaching the brain, the supplement did not improve cognitive performance or brain structure over two years, raising new questions about how DHA is used within the brain.

DHA is a fatty acid that is part of the nerve cell membrane, playing a key role in synaptic function and modulating neuroinflammation. Its levels tend to be lower in the presence of dementia-linked changes like amyloid deposition and cognitive decline, and in patients with late-onset Alzheimer's disease (AD).