Omega-3 Supplements Linked to Faster Cognitive Decline in Older Adults: Study
China: A recent study using data from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) reported that omega-3 fatty acid supplementation was associated with faster cognitive decline in older adults.
The study found that individuals taking omega-3 supplements showed a faster decline in cognitive performance on standard measures, including MMSE and ADAS-Cog13.
Importantly, this decline was not linked to classical Alzheimer’s disease markers such as amyloid or tau accumulation. Instead, it was associated with reduced cerebral glucose metabolism, suggesting a possible impact on synaptic function. The authors emphasized that these are observational findings and suggest a need to re-evaluate routine omega-3 use for cognitive protection.
Published in the Journal of Prevention of Alzheimer's Disease, the study was led by Zheng-Bin Liao and colleagues from the Third Military Medical University, Chongqing.
To explore this association, researchers conducted a longitudinal analysis using data from the ADNI cohort. Cognitive changes over time were assessed using linear mixed-effects models comparing omega-3 users with non-users. Mediation analyses were also performed to determine whether the relationship was driven by amyloid deposition, tau pathology, structural brain changes, or alterations in cerebral glucose metabolism.
The researchers reported the following findings:
- Omega-3 supplementation was consistently associated with faster cognitive decline over time.
- Supplement users showed a more rapid decrease in MMSE scores compared with non-users.
- ADAS-Cog13 scores worsened more quickly among individuals taking omega-3 supplements.
- Clinical Dementia Rating Sum of Boxes (CDR-SB) scores also increased at a faster rate in supplement users.
- All observed differences in cognitive decline measures were statistically significant.
- The association between omega-3 supplementation and cognitive decline was not explained by amyloid accumulation.
- Tau pathology also did not mediate the observed relationship.
- No significant mediation was observed through gray matter atrophy.
- These findings suggest omega-3 supplementation did not influence classical Alzheimer’s disease pathological changes.
- Reduced glucose metabolism in Alzheimer’s-vulnerable brain regions emerged as the key mediating factor.
- FDG-PET imaging showed that brain hypometabolism significantly contributed to the association between omega-3 use and cognitive decline.
- Impaired glucose metabolism accounted for approximately 30% to 40% of the observed effects across cognitive outcomes.
The findings challenge the widely held assumption that omega-3 fatty acids are uniformly beneficial for cognitive health in aging populations. While these nutrients are often promoted for neuroprotection, the study suggests that their effects may be more complex and potentially context-dependent.
The authors emphasized that the results should not be interpreted as definitive evidence of harm, given the observational design of the study. However, they highlighted the need for further controlled research to better understand the biological impact of long-term omega-3 supplementation on brain metabolism and cognitive aging.
"The study suggests that omega-3 supplementation may be associated with faster cognitive decline in older adults, potentially through mechanisms involving impaired cerebral glucose metabolism rather than classical Alzheimer’s disease pathology," the authors concluded.
Reference:
Liao, Z., Hu, Z., Zeng, G., Chen, J., Li, X., Liu, Y., Yao, X., & Wang, Y. (2026). The association between omega-3 supplementation and cognitive decline in older adults. The Journal of Prevention of Alzheimer's Disease, 13(6), 100569. https://doi.org/10.1016/j.tjpad.2026.100569
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