Docosahexaenoic acid, the most abundant omega3 fatty acid in the brain, plays a role in cognitive development, learning ability, neuronal membrane plasticity, synaptogenesis, and neurogenesis, all of which are involved in synaptic transmission and the well-being of normal brain functions, and search on the functionality is still in progress.

Establishment of prevention and treatment of neuropsychiatric illnesses, such as dementia is not easy, but from numerous basic and epidemiological studies, increase of omega3 fatty acid dietary intake is reported likely to prevent the onset of dementia.

This paper is outlined the relevance of cognitive function and omega3 fatty acids, especially docosahexaenoic acid, and the possibility of preventive effect of the fatty acid on dementia.