Omega-3 supplementation was associated with significantly accelerated cognitive decline in older adults, potentially mediated by FDG hypometabolism in AD-vulnerable regions rather than classical AD pathologies.
Omega-3 supplementation was associated with significantly accelerated cognitive decline as measured by MMSE scores.
Omega-3 supplementation was associated with faster increases in ADAS-Cog13 and CDR-SB scores, indicating accelerated cognitive decline.
The association between omega-3 supplementation and cognitive decline was not mediated by amyloid-beta deposition, tau pathology, or gray matter atrophy.
Longitudinal FDG hypometabolism within AD-vulnerable regions served as a significant mediating pathway between omega-3 supplementation and cognitive decline.
The authors conclude that omega-3 supplementation may adversely affect cerebral synaptic function in older adults rather than influencing classical AD proteinopathies.
This research suggests that taking omega-3 fatty acid supplements may actually be associated with faster cognitive decline in older adults, rather than protecting against it. Using data from a large, established Alzheimer's disease research database (ADNI), the researchers tracked participants over time and found that those who took omega-3 supplements showed faster worsening on three different standard cognitive tests compared to those who did not take the supplements. This finding goes against the widely held belief that omega-3 supplements are broadly beneficial for brain health. The researchers also investigated why this association might exist by looking at established Alzheimer's disease brain changes, including amyloid plaques, tau tangles, and brain shrinkage. Surprisingly, none of these classic Alzheimer's markers explained the relationship. Instead, the link was partially explained by reduced brain energy metabolism (measured by FDG-PET scans) in brain regions known to be vulnerable in Alzheimer's disease — a marker closely tied to how well brain synapses (connections between nerve cells) are functioning. This metabolic decline accounted for roughly 19% to 41% of the total observed effect on cognition, depending on which cognitive test was used. This research suggests that omega-3 supplementation in older adults warrants careful reconsideration, as its effects on brain health may be more complex or even harmful than previously thought, possibly by negatively affecting how brain cells use energy. However, as an observational study, it cannot definitively prove that omega-3 supplements cause cognitive decline — other factors, such as people with early cognitive concerns being more likely to take supplements, could influence the results. The authors call for cautious reassessment of widespread omega-3 use for cognitive protection.
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Upload Your LabsLiao Z, Hu Z, Zeng G, Chen J, Li X, Liu Y, et al.. (2026). The association between omega-3 supplementation and cognitive decline in older adults.. The journal of prevention of Alzheimer's disease. https://doi.org/10.1016/j.tjpad.2026.100569