Adult brain neurogenesis and depression.

The waning and waxing of neurogenesis in brain areas such as the dentate gyrus is proposed as a key factor in the descent into and recovery from clinical depression, respectively. A decrease in neurogenesis could occur due to genetic factors, stress (especially because of the involvement of adrenal corticoids), and/or a decline in serotonergic neurotransmission. An increase in neurogenesis could be brought about by several factors, but especially those that activate the serotonin 5-HT(1A) receptor. The possible interaction of immune system factors, especially the proinflammatory cytokines, with adult brain neurogenesis is discussed. Copyright 2002 Elsevier Science (USA)