Review article
Adult neurogenesis and depression

Adult neurogenesis (ANGE) is a process of generating new neurons in the brains of adult mammals, including humans. It takes place, e.g., in the subgranular zone of the dentate gyrus in the hippocampal formation. The function of the new neurons is not fully explained; however, they are considered to play an important role in learning and memory processes. There is also evidence that ANGE can mediate the response of hippocampal formation to stress, preventing the onset of depression. Besides, newly-generated neurons seem to play an important role in therapeutic action of antidepressants (AD). Results from animal models and human studies, confirming and questioning the hypothesis of a key connection between depression and ANGE, are presented. It is not clear whether the suppression of the production of new neurons influences the pathogenesis of depression and it seems that some other factors are more important. However, it is likely that the level of ANGE is important in treatment of at least some forms of depression. Several experiments, using animal models, have shown that AD, mood stabilizers or other depression therapies increase the level of ANGE. Also, blocking the generation of new neurons abolishes their therapeutic effect. Nevertheless, some recent publications question the significance of ANGE in AD action. The discrepancies described herein, concerning the significance of ANGE in aetiology and treatment of depression, may reflect the complexity of the depressive disorder. This complexity is manifested by the different response (or no response) to various AD and other depression therapies in human patients.