30 September 2010
Beneficial effects of Docosahexaenoic Acid Acid on Cognition in Age-related Cognitive Decline
Yurko-Mauro , K. et al., Alzheimer’s and Dementia , in press , 2010
Clinical Research Dept., Martek Biosciences Corp., Columbia, Maryland, USA
The primary objective of this clinical trial was to determine the effect of DHA (docosahexaenoic acid) supplementation on improving cognitive functions in healthy older adults with ARCD (age-related cognitive decline). For this purpose , a randomized double-blind, placebo-controlled study was conducted at 19 U.S. clinical sites involving 485 healthy subjects (ages equal to or greater than 55 years). The subjects were randomly assigned to receive a placebo (control group) or 900 mg DHA as an oral supplement for 24 weeks. The primary measured outcome throughout this trial as a measure of cognitive performance was the CANTAB Paired Associate Learning (PAL) assessment which is a visuospatial learning and episodic memory test.
Relative to the control (placebo) group, the DHA-supplemented subjects exhibited significantly improved learning and memory function in ARCD. The authors concluded that DHA ‘ is a beneficial supplementation that supports cognitive health with aging’ .
Dr. Holub’s Comments :
Based on the two-fold improvement in the PAL errors with DHA supplementation in this clinical trial (relative to the controls), it can be estimated that this represents a net improvement of 3 years cognitively (when compared to age-associated norms ). It is noted that current average intakes of DHA in North American adults is approx. 80 mg/person/day which is much below the 900 mg /person/day as used in the present study.
Candidate sources of DHA for closing this ‘nutrition gap’ if desired include fish/seafood ,functional foods enriched in DHA , and supplementation. Future studies are needed to determine if lower intakes of DHA may improve age-related cognitive decline and to determine if the intake of various amounts of DHA plus EPA versus DHA alone is desirable in preserving or enhancing learning and memory abilities in the elderly.