A – 96 The Relationship Between Omega-3 and Regional Brain Volume in Healthy Older Adults

Abstract Objective Omega-3 fatty acids have been linked to brain health in the aging population, yet the direct relationship between omega-3 levels and brain volume remains unclear. This study investigates whether omega-3 red cell blood count (RBC) predicts brain volume in healthy older adults. Method Forty participants (M=76.25, SD=8.29; 48.9% female) from the Adventist Health Study-2 Cognitive and Neuroimaging Substudy completed brain MRI and omega-3 blood tests. Docosahexaenoic acid (DHA), alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and an omega-3 Index (sum of DHA and EPA) were extracted. Brain volume was assessed using Freesurfer analysis of 3D T1-weighted MPRAGE sequences on a 3T Siemens MRI. Linear regressions were performed to examine relationships between omega-3 and regional brain volume, controlling for age and sex. Results The omega-3 Index was positively associated with white matter volume (β=.27, p=.04), and EPA was positively associated with right entorhinal volume (β=.29, p=.03) and white matter (β=.26, p=.05). DHA on its own was not significantly associated with regional brain volumes, though there was a trending association with white matter (β=.24, p=.06). Conversely, ALA was negatively associated with gray matter (β=-.23, p=.04) and right frontal pole volume (β=-.32, p=.05). Conclusion These findings suggest that higher levels of DHA and EPA may help preserve brain volume in older adults, while higher ALA levels may be associated with reduced brain volume. This inverse relationship may reflect inefficient conversion of ALA to DHA and EPA in older age, thereby limiting the neuroprotective effects.