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

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.