CNS target engagement of high-dose DHA supplementation in older adults at risk for dementia: a randomised, double-blind, placebo-controlled trial
Abstract
Background: APOE ε4 carriers have increased Alzheimer's disease risk and altered omega-3 metabolism. No large-scale prevention trials have tested high-dose docosahexaenoic acid (DHA) supplementation specifically in non-demented APOE ε4 carriers with low baseline omega-3 intake for early intervention.
Methods: We conducted a phase IIa 24-month, randomised, double-blind, placebo-controlled trial (NCT03613844) at the University of Southern California between September 2018 and May 2024. Participants aged 55-80 years without dementia, low dietary DHA intake (<200 mg/day), and ≥1 dementia risk factor were stratified by cerebrospinal fluid (CSF) collection willingness into lumbar puncture (LP) or no-LP arms. Within each arm, participants were randomised 1:1 to receive 2 g/day DHA or placebo, stratified by APOE ε4 status. Primary outcome was the 6-month CSF DHA-to-arachidonic acid (AA) ratio change. Secondary and exploratory outcomes included 24-month neuroimaging and cognitive measures.
Findings: Of 739 screened individuals, 365 participants were randomised (181 LP arm, 184 no-LP arm). Mean age was 66.4 years (SD 5.7), 210 (58%) were female, 142 (39%) were Hispanic, 173 (47%) were APOE ε4 carriers. DHA supplementation increased CSF DHA/AA ratio at 6 months vs placebo (0.17 [95% CI 0.15-0.18] vs -0.02 [95% CI -0.04 to -0.0004]; difference 0.19 [95% CI 0.16-0.21]; p < 0.0001), independent of APOE ε4 status (interaction p = 0.71). Dropout was 38%, mainly due to COVID-19. No treatment…
How strong is the evidence?
Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 2 of 5 (High · randomized trial). Randomized trials of a reasonable size are the strongest single-study design. Reported size: 739 participants or records.
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