Brain tissue contains about 60 percent fat. Two essential fatty acids, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are necessary for the proper development and function of the brain and the eyes. Deficiencies of these long-chain fatty acids can lead to psychiatric disorders, including depression. Fortunately, these fatty acids are found in fish oil, and eating fatty fish such as salmon, mackerel or sardines several times per week can provide enough of these necessary nutrients to maintain good health.
Essential fatty acids are called “essential” because they have to be obtained from the food that we eat and cannot be created from monounsaturated or saturated fats. Strict vegetarians who do not consume animal products, including fish, can potentially develop omega-3 deficiency. However, flax seed oil is a good vegetable source of alpha linolenic acid (ALA) which is an omega-3 fatty acid with 18 carbon atoms that can be converted by the body into EPA with 20 carbons, and DHA with 22 carbons, although at low efficiency.
A recent study tried to find out why higher dietary intake of omega-3 fats and higher blood levels of DHA and EPA have been associated with a reduced risk for dementia. The researchers performed cognitive tests and measured the brain volume of 1,575 dementia-free participants of the Framingham Study. The participants with the lowest blood levels of DHA had lower total brain volumes. Participants with lower omega-3 levels also had lower scores on tests of visual memory, abstract thinking, and executive function which includes cognitive processes such as planning, memory, attention span, problem solving and verbal reasoning. The study concludes that lower blood levels of DHA are associated with smaller brain volumes and cognitive impairment even in persons free of clinical dementia.
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