Essential fatty acids as potential anti-inflammatory agents in the treatment of affective disorders.

In the last two decades, many studies have demonstrated that increased inflammatory responses occur in patients with affective disorders, which could contribute to the dysfunction of neuroendocrine and neurotransmission in these diseases. The evidence consequently suggests that drugs or natural products with anti-inflammatory properties should be developed to treat the illness. Among several candidates that modulate the neuro-immune network, omega-(n)-3 essential unsaturated fatty acids have emerged as effective treatments for affective disorders. Because these fatty acids can influence membrane structure, reduce inflammation and regulate protein and gene expressions, their effects seem promising. In this chapter, the newest findings that support the inflammatory theory of affective disorders have been first selected and reviewed. Secondly, the role of n-3 fatty acids in the immune system and brain has been introduced and then the possible mechanisms by which n-3 fatty acids attenuated symptoms of depression are discussed by the insight of the results from the animal studies. Finally, the clinical effects of n-3 fatty acids on major, bipolar and postpartum depression are summarized. Furthermore, the chapter points out the limitations and future research in this area.