GUELPH, CANADA. Dementia now affects about 47% of the population over 80 years of age in Western countries. The incidence of Alzheimer's disease, a leading cause of dementia, is growing especially rapidly. There is no cure for Alzheimer's disease (AD) and it is not at all clear what causes it. Researchers at the University of Guelph now report that they have found low levels of long-chain polyunsaturated fatty acids, notably DHA (docosahexaenoic acid, which is found in fish oil supplements) in people suffering from AD and dementia.
The study involved 84 people (aged 80 years or older) who were given a thorough clinical evaluation. Nineteen of the people were diagnosed as having AD, 10 as having non-AD dementia, 36 were characterized as non-demented but cognitively impaired, and 19 had normal cognitive functioning. Blood samples were obtained from all participants and analyzed for fatty acids in the phospholipid phases of the plasma. The researchers observed significantly lower levels of eicosapentaenoic acid (also known as EPA; by about 42%), DHA (by 17-33%) and total omega-3 fatty acids (by 23-28%) in the plasma phospholipids phase of the patients with AD, other dementia and cognitive impairment (non-demented) than in the normal controls. DHA is highly concentrated in the cerebral cortex and a deficiency in blood plasma is likely to translate into a deficiency in the brain. Fish oil supplements contain both DHA and EPA.
Other research has confirmed the association between low DHA and EPA levels and impaired cognitive function. Other studies have found that taking fish oil supplements improves mood, cooperation, appetite, sleep, and short-term memory in AD patients. The Guelph researchers conclude that an effort should be made to increase the intake of fish or fish oil supplements in the population at large and the elderly in particular.
Conquer, Julie A., et al. Fatty acid analysis of blood plasma of patients with Alzheimer's disease, other types of dementia, and cognitive impairment. Lipids, Vol. 35, December 2000, pp. 1305-12.