Omega‐3 blood biomarkers relate to brain glucose uptake in individuals at risk of Alzheimer's disease dementia

Abstract INTRODUCTION Brain glucose hypometabolism is a preclinical feature of Alzheimer's disease (AD). Dietary omega‐3 fatty acids promote brain glucose metabolism, but clinical research is incipient. Circulating omega‐3s objectively reflect their dietary intake. METHODS This was a cross‐sectional study in 320 cognitively unimpaired participants at increased risk of AD dementia. Using lipidomics, we determined blood docosahexaenoic (DHA) and alpha‐linolenic (ALA) acid levels (omega‐3s from marine and plant origin, respectively). We assessed brain glucose metabolism using [18‐F]‐fluorodeoxyglucose (FDG) positron emission tomography (PET). RESULTS Blood ALA directly related to FDG uptake in brain areas known to be affected in AD. Stronger associations were observed in apolipoprotein E ε4 carriers and homozygotes. For DHA, significant direct associations were restricted to amyloid beta–positive tau‐positive participants. DISCUSSION Blood omega‐3 directly relate to preserved glucose metabolism in AD‐vulnerable brain regions in individuals at increased risk of AD dementia. This adds to the benefits of omega‐3 supplementation in the preclinical stage of AD dementia. Highlights Blood omega‐3s were related to brain glucose uptake in participants at risk of Alzheimer's disease (AD) dementia. Complementary associations were observed for omega‐3 from marine and plant sources. Foods rich in omega‐3 might be useful in early features of AD.