# USC study on fish oil and Alzheimer’s risk > Live situation record from CLSTR: https://clstr.news/situations/usc-study-on-fish-oil-and-alzheimers-risk > Updated: 2026-10-25T20:14:16.000Z. Sources: 10. Developments: 2. Researchers at the University of Southern California (USC) conducted a two-year clinical trial involving 365 adults aged 55 to 80 to determine if high-dose omega-3 fish oil supplements could prevent cognitive decline or brain shrinkage in those at risk for Alzheimer’s disease. The study, published in the journal eBioMedicine, found that while daily supplementation of 2000 mg of docosahexaenoic acid (DHA) successfully increased DHA concentrations in the cerebrospinal fluid by approximately 17 percent, it provided no measurable clinical benefits. Participants receiving the supplements showed no improvements in thinking skills, memory, or cognitive function compared to a placebo group, nor did the supplements slow brain shrinkage. Dr. Hussein Naji Yassine, director of the USC Center for Personalized Brain Health, noted that although omega-3s are essential for brain cell connections, the results do not support their use as a preventive measure against Alzheimer’s. The findings challenge common marketing claims regarding these products. The trial specifically included participants who rarely consumed fish, nearly half of whom carried the APOE4 genetic variant, a significant risk factor for Alzheimer's. Dr. Yassine observed that while the molecules reach the brain, they do not appear to protect against cognitive decline or the structural brain changes associated with the disease. Lead researcher Dr. Hussein Naji Yassine emphasized that these results do not suggest omega-3s are useless or that fish consumption is unnecessary, but rather that high-dose supplementation may not serve as an effective preventative measure for cognitive decline. Brain scans specifically indicated that the supplements failed to slow the shrinkage of the hippocampus, a region critical for memory formation. ## Timeline ### 2026-10-25: University of Southern California study finds fish oil supplements do not improve memory A USC study involving 365 older adults found that daily high-dose omega-3 supplements failed to improve memory or slow hippocampal shrinkage in those at risk for Alzheimer's. 5 sources. https://clstr.news/cluster/usc-study-finds-fish-oil-supplements-do-not-improve-memory ### 2026-10-22: Fish oil supplements fail to protect memory in older adults, study finds A USC study found that high-dose fish oil supplements do not improve memory or prevent brain shrinkage in older adults at risk of Alzheimer's disease. 5 sources. https://clstr.news/cluster/fish-oil-supplements-fail-to-protect-memory-in-older-adults-study-finds --- Cite as: USC study on fish oil and Alzheimer’s risk. CLSTR, https://clstr.news/situations/usc-study-on-fish-oil-and-alzheimers-risk