Higher RBC EPA + DHA corresponds with larger total brain and hippocampal volumes: WHIMS-MRI study.
Level 3 - non-randomized controlled study
Prospective observational cohort analysis within a randomized trial population
PubMed 24453077 · doi:10.1212/WNL.0000000000000080
What was done
In an ancillary study to the Women's Health Initiative Memory Study (WHIMS-MRI), baseline red blood cell (RBC) levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were measured in 1,111 postmenopausal women. Structural brain MRI was conducted 8 years later to evaluate total brain volume, regional volumes (including hippocampal volume), and ischemic lesion volume. Linear mixed models with multiple imputations were adjusted for hormone therapy assignment, time since randomization, demographic factors, total intracranial volume, and cardiovascular risk factors.
What was found
A 1 standard deviation (SD) higher RBC EPA + DHA (omega-3 index) level was associated with 2.1 cm³ larger total brain volume (p = 0.048). Individually, DHA showed a marginal correlation (p = 0.063) and EPA was not significantly correlated (p = 0.11) with total brain volume. Omega-3 levels were not associated with ischemic lesion volumes. For regional volume, a 1 SD higher omega-3 index was associated with 50 mm³ greater hippocampal volume (p = 0.036), and women in the highest quartile had 159 mm³ larger hippocampal volumes compared to the lowest quartile (p = 0.034).
Why it matters
These findings suggest that higher circulating omega-3 fatty acid levels may be prospectively linked to preserved total brain and hippocampal volumes in older women, pointing to a potential dietary biomarker for resisting age-related neurodegeneration.
Limits
The study is observational and cannot establish causality. MRI was only assessed 8 years post-baseline without a baseline MRI to quantify actual rates of volume loss over time. The cohort was restricted entirely to postmenopausal women enrolled in a hormone therapy trial, limiting generalizability to men or younger populations. Several statistical findings were borderline significant (p ≈ 0.03 to 0.05).
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