Authors' objectives:

The aim of this study was to assess the effect of omega-3 fatty acids on 1) cognitive function in normal aging 2) the incidence of dementia, 3) treatment of dementia, 4) the incidence of several neurological diseases, and 5) clinical outcomes related to the progression of multiple sclerosis.

Authors' results and conclusions: 1) A single cohort study has assessed the effects of omega-3 fatty acids on cognitive function with normal aging and found no association for fish or total omega-3 consumption. 2 and 3) In four studies (3 prospective cohort studies and one RCT) that assessed the effects of omega-3 fatty acids on incidence and treatment of dementia, a trend in favor of omega-3 fatty acids (fish and total omega-3 consumption) toward reducing risk of dementia and improving cognitive function was reported. 4) Two studies, one cohort and one case-control, that assessed the effects of omega-3 fatty acids on incidence of MS were inconclusive. A single cohort study evaluating the effects of omega-3 fatty acids on incidence of Parkinson's disease found no significant association between dietary intake of omega 3 fatty acids (fish, ALA, EPA, or DHA) and Parkinsons. Another single case-control study found a significant association between maternal fish consumption at least once a week throughout pregnancy and a lower risk of cerebral palsy in offspring. 5) In one RCT, omega-3 fatty acids (fish, ALA, EPA, DHA) had no effect on the progression of multiple sclerosis; two single-arm open-label trials showed improvement in disability with omega-3 supplementation.

Authors' recommendations: The quantity and strength of evidence for effects of omega-3 fatty acids on the neurological conditions assessed vary greatly. Due to the small number of studies that met our inclusion criteria, further research is necessary before substantive conclusions can be drawn. The paucity of evidence in this area suggests that a great deal of epidemiological and clinical research remains to be done before any conclusions can be drawn or policy recommendations can be made regarding the health effects of omega-3 fatty acids on normal cognitive function with aging, dementia, and neurological diseases.

Authors' methods: Systematic review

Project Status: Completed

URL for project: http://www.ahrq.gov/clinic/tp/o3cogntp.htm

Year Published: 2005

English language abstract: An English language summary is available

Publication Type: Not Assigned

Country: United States

Organisation Name: Agency for Healthcare Research and Quality

Contact Address: Center for Outcomes and Evidence Technology Assessment Program, 540 Gaither Road, Rockville, MD 20850, USA. Tel: +1 301 427 1610; Fax: +1 301 427 1639;

Contact Name: martin.erlichman@ahrq.hhs.gov

Contact Email: martin.erlichman@ahrq.hhs.gov

Copyright: Agency for Healthcare Research and Quality (AHRQ)