Beneficial effects of docosahexaenoic acid on cognition in age-related cognitive decline
Received 13 August 2009; received in revised form 6 January 2010; accepted 22 January 2010. published online 03 May 2010. Corrected Proof
Abstract
Background
Docosahexaenoic acid (DHA) plays an important role in neural function. Decreases in plasma DHA are associated with cognitive decline in healthy elderly adults and in patients with Alzheimer's disease. Higher DHA intake is inversely correlated with relative risk of Alzheimer's disease. The potential benefits of DHA supplementation in age-related cognitive decline (ARCD) have not been fully examined.
Objective
Determine effects of DHA administration on improving cognitive functions in healthy older adults with ARCD.
Methods
Randomized, double-blind, placebo-controlled, clinical study was conducted at 19 U.S. clinical sites. A total of 485 healthy subjects, aged ≥55 with Mini-Mental State Examination >26 and a Logical Memory (Wechsler Memory Scale III) baseline score ≥1 standard deviation below younger adults, were randomly assigned to 900 mg/d of DHA orally or matching placebo for 24 weeks. The primary outcome was the CANTAB Paired Associate Learning (PAL), a visuospatial learning and episodic memory test.
Results
Intention-to-treat analysis demonstrated significantly fewer PAL six pattern errors with DHA versus placebo at 24 weeks (difference score, −1.63 ± 0.76 [−3.1, −0.14, 95% CI], P = .03). 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 DHA levels doubled and correlated with improved PAL scores (P < .02) in the DHA group. DHA was well tolerated with no reported treatment-related serious adverse events.
Conclusions
Twenty-four week supplementation with 900 mg/d DHA improved learning and memory function in ARCD and is a beneficial supplement that supports cognitive health with aging.
Conflicts of Interest Disclosure: With the exception of Drs. Dror Rom, Andrew Blackwell, and Mary Stedman, the other authors are employed by Martek Biosciences Corporation. Dr. Rom and Dr. Blackwell were consultants to the study. The participating clinical investigators are listed as a group in the acknowledgement section of the manuscript.
Contributors: Blackwell, Nelson, Rom, Yurko-Mauro contributed to the study concept and design. Blackwell, McCarthy, Nelson, Rom, Yurko-Mauro and Stedman participated in study conduct and collection of the data. Rom had responsibility for the statistical analysis. Blackwell, Nelson, Rom, Ryan, Salem, Yurko-Mauro contributed to the interpretation of data. Blackwell, Ryan, Yurko-Mauro contributed to the drafting of the manuscript and McCarthy, Nelson, Rom, Ryan, Salem, Stedman and Yurko-Mauro participated in the revision of the manuscript. The corresponding author had full access to all data in the study after study unblinding, and had final responsibility for the writing of the report and the decision to submit for publication. The study was funded by Martek Biosciences Corporation.
ABSTRACT