Still No Support for Omega-3 in Alzheimer’s
Supplementation (or treatment, depending on your semantic viewpoint) with the omega-3 fatty acid DHA does not improve the symptoms of Alzheimer disease, according to a newly published, well-controlled study in JAMA. This latest conclusion supports results from at least 1 other similarly controlled AD study (conducted by the Karolinska Institute), which showed that DHA supplementation (along with EHA) does not improve cognition or other AD performance measures.*
In the multicenter JAMA study (conducted between November 2007 and May 2009 at 51 US sites), 402 patients with mild-moderate AD received randomly assigned DHA (2 g/d) or placebo in double-blind fashion. At 18 months of follow-up, changes in the standard measures of cognition (ADAS-cog, CDR) were not significantly different between the 2 treatment arms (in both cases with both treatments, scores increased—highlighting the importance of the placebo effect in AD). The rate of brain atrophy (via volumetric MRI in 102 subjects) was also not affected by DHA supplementation. Brain volume declined similarly with each treatment, reflecting the objective, inexorable progression of AD.
A major caveat of the study: Completion rate, 73% (295/402) was low and, according to the authors, probably related to a perceived lack of treatment efficacy.
The study, based out of Oregon Health and Science University, was supported by a grant from the National Institute on Aging and Martek Biosciences, which supplied the supplements (or treatments), the laboratory measurements (plasma and CSF measures of fatty acids), and partial funding for the MRI assessments.
ADAS-cog = Alzheimer Disease Assessment Scale , cognitive subscale; CDR = Clinical Dementia Rating; DHA = docosahexaenoic acid; EHA = eicosapentaenoic acid.
* Except in some subgroup analyses.
Image of cod liver oil capsules from Wikipedia.