Dementia, or loss of cognitive function, increases in frequency as people age, affecting 5 to 8 percent of people over age 65 and nearly half of those over 80, according to the Cleveland Clinic. Despite its prevalence, dementia is not considered a normal part of aging. Alzheimer's disease, the most common type of dementia, accounts for 50 to 70 percent of all dementia cases. Omega-3 fatty acids, found primarily in fish and fish oil, have shown some early promise in treating dementia, especially Alzheimer's, but more recent studies have not confirmed its benefit.
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Dementia has many causes. Alzheimer's disease is caused by plaque formation in the brain. Traumatic brain injury, vascular blockages in the brain that interfere with blood flow, diseases such as Huntington's disease or Parkinson's disease, alcohol abuse and brain tumors can all cause dementia. Omega-3 fatty acids can decrease inflammation, increase blood flow and decrease clot formation in the blood vessels. Most studies have focused on supplementing with docosahexaenoic acid, or DHA, the primary omega-3 fatty acid found in the brain.
Effects
Low levels of DHA have been associated with an increased risk of dementia in some studies. Researchers from the University of Guelph in Canada, who published their results in the December 2000 issue of "Lipids," found that people with dementia had lower serum DHA levels than elderly subjects with normal cognitive functioning.
Recent Results
A study published in the November 2010 issue of "JAMA" by researchers from Oregon Health and Science University evaluated the effects of 2 g per day of DHA compared to placebo in 402 subjects randomized to receive active drug or placebo. The 18-month study found that DHA had no effect on cognitive functioning in the group, which included people with mild to moderate Alzheimer's, as determined by changes in the Alzheimer's Disease Assessment Scale or the Clinical Dementia Rating. A previous meta-analysis conducted by the United States Department of Health found that, out of 497 available studies, 12 relevant studies had useable data to assess the effects of omega-3 fatty acids on brain function. Of the four studies dealing with dementia, one showed no benefit and three others showed a positive trend toward reduced dementia risk and improved functioning.
Considerations
Researchers from the Oregon Health and Science University concluded that further studies are needed to assess the effects of omega-3 fatty acids given to prevent or decrease dementia before the disease becomes apparent. Many more studies need to be done before a potential benefit for omega-3 fatty acids can be determined or ruled out, the U.S. Department of Health and Human Resources study concluded.
References
- Oregon Health and Science University; DHA 'Fish Oil' Supplements Do Not Appear to Slow Cognitive, Functional Decline in Alzheimer's Disease; November 2010
- U.S. Department of Health and Human Services; Omega-3 Fatty Acids, Effects on Cognitive Functions ; February 2005
- "Lipids;" Fatty Acid Analysis of Blood Plasma of Patients with Alzheimer's Disease, Other Types of Dementia, and Cognitive Impairment; J. Conquer, et al.; December 2000
- Cleveland Clinic: Types of Dementia
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