A study has just been published in JAMA which found that giving supplements of Omega-3 (DHA) to people with mild to moderate Alzheimer’s disease did not produce any reduction in the rate of cognitive decline, indicating that supplementation in this group would not be warranted. In this study a group of 402 people with either mild to moderate Alzheimer’s disease, 60% of the group received supplementation of 2 gm of DHA, the other 40% received placebo over an 18-month period. They underwent cognitive testing using the Alzheimer’s Disease Assessment Scale and Clinical Dementia Rating. A sub sample of 102 subjects also underwent functional MRI scanning to look for the rate of cortical atrophy. The study found no benefit of the supplementation on the ADAS-Cog score or rate of brain atrophy during the time of the trial. Many people currently take Omega-three's as a supplement, commonly as fish oil capsules and include fish in their diet on the basis of other studies, which have suggested that this is a way to reduce one’s personal risk of developing dementia or Alzheimer’s disease . So should we stop doing this?
Absolutely not. The difference here in this study is that they were looking at people who had been already diagnosed with Alzheimer's.
An earlier study in 2006 at the respected Karolinska Institute had previously looked to see if DHA and EPA (Omega-3) supplements given to a group of people with either diagnosed Alzheimer’s disease or a small sub-group with very early cognitive impairment would be useful as a means of slowing the progression of the disease. This study also found no benefit of supplementation in those already diagnosed with Alzheimer’s. However those who only had mild cognitive impairment did show some benefit. They had less cognitive decline on mental testing than a control group over a 6-month period, and when the control group received the supplements over a second 6-month period their rate of decline decreased as well. Here the authors proposed that is may be because the omega-3 fatty acids exert an anti–inflammatory effect. Inflammation is believed to be part of the neuropathological development of Alzheimer’s. The comment then was perhaps the anti-inflammatory effect of the Omega-3’s could only be of use prior to too much neuropathological change being evident. The 2006 study only included a very small number of subjects (32 people) Larger studies with bigger cohorts of those with mild cognitive impairment as well as those at risk of Alzheimer’s are needed to see if Omega 3-s may be of benefit in halting the earlier progression of the disease. The conclusion from the latest study supports the literature that supplementation with DHA is not beneficial in established mild to moderate Alzheimer’s.
Meanwhile there is plenty of evidence to support continuing to enjoy eating fish and taking Omega-3 supplements as a means of reducing our relative risk of developing cognitive decline and dementia.
Journal References: 1. K. Yaffe. Treatment of Alzheimer Disease and Prognosis of Dementia: Time to Translate Research to Results. JAMA: The Journal of the American Medical Association, 2010; 304 (17): 1952 DOI: 10.1001/jama.2010.1625 2. J. F. Quinn, R. Raman, R. G. Thomas, K. Yurko-Mauro, E. B. Nelson, C. Van Dyck, J. E. Galvin, J. Emond, C. R. Jack, M. Weiner, L. Shinto, P. S. Aisen. Docosahexaenoic Acid Supplementation and Cognitive Decline in Alzheimer Disease: A Randomized Trial. JAMA: The Journal of the American Medical Association, 2010; 304 (17): 1903 DOI: 10.1001/jama.2010.1510 3. JAMA and Archives Journals (2006, October 11). Omega-3 Fatty Acids May Slow Cognitive Decline In Some Patients With Very Mild Alzheimer's Disease. ScienceDaily. Retrieved November 4, 2010, from http://www.sciencedaily.com¬ /releases/2006/10/061010022736.htm