Abstract
Docosahexaenoic acid (DHA, 22 : 6n-3), an essential n-3 polyunsaturated fatty acid, is one of the integral components of neural membrane phospholipids and is essential for normal neurological development and vision. DHA deficiency markedly affects neurotransmission, activities of membranebound enzymes and ion channel, gene expression and synaptic plasticity; it is thus associated with some neurological dysfunction in aging, Alzheimer's disease (AD), depression and peroxisomal disorders. Deficiency in dietary DHA induces loss of discriminative learning ability; thus intake of DHA may restore this loss. Epidemiological studies show a relation between the ingestion of fish oils and AD, suggesting neuroprotective consequences of the oil, especially of DHA. Although the molecular mechanism of DHA involvement in neurological disorders remains unknown, dietary administration of DHA improves lost learning ability in animals, and protects against and ameliorates the impairment of learning ability in AD model rats and mice. The improvement effect of dietary DHA on memory/learning ability and its application to AD and depression in neurological dysfunction is reviewed here.
