DHA in Fish Oil Does Not Slow Alzheimer’s Decline


Omega-3 fatty acids such as docosahexaenoic acid (DHA) found in fish oil has been linked in previous studies with many brain health benefits including a lower risk of dementia and cognitive decline. Unfortunately, a new study, however, has found that those already diagnosed with mild to moderate Alzheimer’s may not benefit from added supplementation of DHA.

Despite Increased DHA Levels, Decline No Different Between Supplements and Placebo

Cognitive decline refers to a lower awareness, judgment, and thinking process that occur in dementias such as Alzheimer’s disease. DHA is a primary component of brain cells, and it was thought that by increasing its consumption, the cells would stay healthy longer to prevent such decline.

Researchers at the Oregon Health and Science University and the Portland VA Medical Center studied 402 patients with mild/moderate Alzheimer’s disease (average age 76 years) at 51 clinical research centers across the country between November 2007 and May 2009.
Mild to moderate disease indicates that the patients had enough of an impairment to justify a diagnosis, but they were still living at home, interacting with families, and enjoying a good quality of life.

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The patients were randomized to receive either a daily 2 gram tablet that contained DHA or a placebo. At the conclusion of the study, the patients were assessed for functional and cognitive abilities using the ADAS-cog (Alzheimer’s Disease Assessment Scale) and the CDR (the Clinical Dementia Rating). Brain atrophy was measured using MRI scans.

Over the course of the 18-month study, those taking DHA supplements experienced the same rate of cognitive and functional decline as those on the placebo despite showing increased levels of DHA in both blood and cerebrospinal fluid.

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Dr. Joseph F. Quinn MD, lead author and assistant professor of neurology who published the study in the most recent issue of the Journal of the American Medical Association, wrote: “In summary, these results indicate that DHA supplementation is not useful for the population of individuals with mild to moderate Alzheimer disease.”

However, because the study involved those already diagnosed with Alzheimer’s, he mentions that “it remains possible that an intervention with DHA might be more effective if initiated earlier in the course of the disease in patients who do not have overt dementia.

Source Reference:
"Docosahexaenoic Acid Supplementation and Cognitive Decline in Alzheimer Disease - A Randomized Trial"
Joseph F. Quinn, MD; Rema Raman, PhD; Ronald G. Thomas, PhD; Karin Yurko-Mauro, PhD; Edward B. Nelson, MD; Christopher Van Dyck, MD; James E. Galvin, MD; Jennifer Emond, MS; Clifford R. Jack Jr, MD; Michael Weiner, MD; Lynne Shinto, ND; Paul S. Aisen, MD
JAMA. 2010;304(17):1903-1911. doi:10.1001/jama.2010.1510