Adult neurogenesis and depression: an introduction.

The following essay provides a summary of a seminar given on the sixth of November, 2010 at the combined annual congress, held at Brussels of the Centro Studi Psichatrici Vrije Universiteit Brussel, Université Catholique de Louvain & the Bedfordshire Centre for Mental Health Research. The talk aimed to present a brief taster, assuming no prior knowledge, of adult neurogenesis, the formation of new nerve cells, in relation to the aetiology and treatment of depression. The talk begins with an introduction to the principles of adult neurogenesis: from initial investigations by Ramon y Cajal in the 19th century, resulting in a "static brain hypothesis", to their subsequent challenge almost one hundred years later. The potential functional implications emerging, especially in relation to depression, are explored. The fascinating effects of corticosteroids and antidepressants are used as examples to explore the possible roles of neurogenesis that have led some to propose a neurogenic theory of depression. Arguments against this theory are then presented. Finally, a consideration of future opinion: could neurogenesis be less important in the aetiology of depression, but involved in its treatment - a property of antidepressant action rather than a central final aetiological pathway. In this young branch of neuroscience controversy abounds: our understanding of the process itself, its relations and most importantly its implications are all in their infancy. This has allowed for some of the most interesting debate of recent years as to the neurological basis and treatment of affective disorders.