science
Two-Year USC Study Finds High-Dose DHA Supplements Did Not Slow Memory Loss or Brain Shrinkage
A two-year trial at the University of Southern California found that 2,000 mg daily DHA supplements failed to slow cognitive decline or hippocampal atrophy in 365 adults at elevated Alzheimer's risk. Researchers reported a 17 percent rise in cerebrospinal fluid DHA levels but no clinical benefit over placebo.
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A two-year placebo-controlled study at the Keck School of Medicine at the University of Southern California found that daily supplements containing 2,000 mg of docosahexaenoic acid produced no measurable improvement in memory or cognitive function among adults at elevated risk of Alzheimer’s disease.
Usa Today reported that the trial enrolled 365 participants ages 55 to 80. One group received the DHA supplement while the other received a placebo.
After six months, the supplement group showed a 17 percent increase in DHA levels in cerebrospinal fluid, confirming the nutrient reached the brain. Brain imaging and cognitive testing conducted at the end of the study showed no difference between the groups. The hippocampus, a region tied to memory, shrank at similar rates in both arms.
Dr. Hussein Naji Yassine, director of the USC Center for Personalized Brain Health and lead investigator, said the results do not support fish oil supplements as a preventive measure. "We all wish there was a silver bullet for preventing Alzheimer's, but our findings showed that fish oil supplements do not appear to protect brain health," he stated.
Yassine added that the team is now examining how factors such as diet, genetics and overall health affect the brain’s ability to use omega-3s. Researchers noted that a Mediterranean-style diet rich in fish, along with regular exercise and quality sleep, remains the strongest defense against Alzheimer’s disease.
