November 11, 2010 — Supplementation with docosahexaenoic acid (DHA) in older adults who have mild cognitive impairment may improve memory and cognitive function, a randomized controlled trial suggests.
According to the results of the Memory Improvement with Docosahexaenoic Acid Study trial, 900 mg/day DHA given for 24 weeks improved learning and memory function in healthy elderly adults with age-related cognitive decline.
The study, which was funded by Martek Biosciences Corporation, in Columbia, Maryland, manufacturer of the DHA, was initially presented at the Alzheimer's Association International Conference on Alzheimer's Disease in July 2009 in Vienna and reported by Medscape Medical News at that time. It is published in the November issue of Alzheimer's & Dementia.
"There is a good amount of literature out there about the potential health benefits of omega-3 fatty acids on the brain," Karin Yurko-Mauro, PhD, associate director of clinical research at Martek, told Medscape Medical News.
"Data from epidemiological studies show a correlation between omega-3 intake and reduced risk of dementia, and we had some data from work that was done with our DHA in animal models of Alzheimer's disease that showed improvement in behavioral memory tasks. All of this led us to try to look at what DHA supplementation would do in health elderly people."
The study included 485 patients aged 55 years and older enrolled from 19 centers in the United States and randomly assigned to receive 900 mg/day algal DHA or placebo for 24 weeks.
All participants had a subjective memory complaint and were found to have a mild memory deficit, but no dementia, as per objective tests. These tests included the Mini-Mental State Examination (baseline score > 26) and the Logical Memory subtest of the Wechsler Memory Scale (version III, 1997; baseline score >1 SD below younger adults).
3-Year Cognitive Improvement
The primary outcome measure was a change from baseline in CANTAB Paired Associate Learning (PAL), a visuospatial learning and episodic memory test.
A coprimary endpoint was change in CANTAB Pattern Recognition Memory (PRM), a test of visual pattern recognition, but after a preplanned interim analysis revealed that this endpoint did not meet the conditional power threshold of 30%, it was changed to a secondary endpoint, the study authors said.
Other secondary endpoints were CANTAB Verbal Recognition Memory, a test of immediate and delayed verbal memory; CANTAB Stockings of Cambridge, a test of executive function; and CANTAB Spatial Working Memory, a test of spatial retention and search strategy.
After 24 weeks, the researchers found that participants taking DHA supplements made significantly fewer errors on the PAL test. The mean change from baseline in the PAL score was −4.5 in the DHA group compared with −2.4 for the placebo group (P = .032). However, the mean change in the PRM score was −0.9 in both the DHA and placebo groups (P = .573).
DHA supplementation was also associated with improved immediate and delayed Verbal Recognition Memory scores (P < .02), but not working memory or executive function tests.
Plasma phospholipid DHA levels doubled during the study in people taking the supplements and correlated with improved PAL scores (P < .02), and the supplement was well tolerated, with no reported treatment-related serious adverse events.
"With age, the older people are, the more errors they make on a test. But the improvements we saw on the test correlate to about a 3-year cognitive improvement," Dr. Yurko-Mauro said.
So somebody who was 73 was performing like a 70-year old. Our study does point to the fact that algal DHA can be beneficial for healthy aging adults who have a mild memory complaint.
"So somebody who was 73 was performing like a 70-year old. So our study does point to the fact that algal DHA can be beneficial for healthy aging adults who have a mild memory complaint."
Medscape Medical News asked Joseph Quinn, MD, from the Oregon Health and Science University and the Portland VA Medical Center, to comment on this study.
A recent study by Dr. Quinn and colleagues published in the November 3 issue of the Journal of the American Medical Association and reported by Medscape Medical News showed no positive effect of DHA supplementation on disease progression in Alzheimer's disease.
Dr. Quinn first disclosed that he is a coinventor on a patent filed by Martek for the use of DHA for non-E4 Alzheimer's disease (a form of Alzheimer's disease in carriers of the non-APOE4 allele), but that he has waived all royalties associated with the patent.
He then went on to state, "This study is modestly encouraging regarding the potential for DHA for prevention of late life cognitive decline. It is always very difficult to show cognitive benefits in healthy elderly, so that is a strength."
However, he took issue with the study authors' decision to demote their original coprimary endpoint of pattern recognition memory to a secondary endpoint.
"The test of this sort of study is whether the investigators found what they predicted they'd find in advance; in other words, the ultimate test is the ability to show efficacy on the prespecified outcome measures.
These findings represent a post hoc analysis, showing efficacy on just a few outcome measures out of a great many tested. As such, it is still a 'real' result, but weaker than if this was truly a prespecified analysis.
"As the authors disclose in the methods section, they modified their analysis plan midstream based on an interim analysis. This means that their findings represent a post hoc analysis, showing efficacy on just a few outcome measures out of a great many tested. As such, it is still a 'real' result, but weaker than if this was truly a prespecified analysis."
This study was supported by Martek Biosciences Corporation. Dr. Yurko-Mauro is an employee of Martek. Dr. Quinn reports being named as a coinventor on a patent for DHA for the treatment of Alzheimer's disease in APOE4-negative individuals and has waived his personal right to royalties related to this patent.
Alzheimers Dement. 2010;6:456-464. Abstract
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Cite this: DHA Supplementation Improves Memory, Cognitive Function in Elderly - Medscape - Nov 11, 2010.