Brain, Behavior and Epigenetics

Abstract

Major depression and suicide, which is its most severe outcome, are common problems that represent a major burden in our society. The relationship among early life adversity, depression, and suicide has already been well demonstrated, however, the molecular mechanisms mediating this relationship still remain poorly understood. From rat studies, we have recently gained major insight into some of the genomic processes that modify behavior, which result from early social environmental experiences. These processes, collectively referred to as epigenetics, are defined by chemical modifications taking place around the DNA molecule that alter the coding capacity of a gene. Accordingly, this is believed to represent an interface through which the environment can act upon our genome to modify gene expression and behavior. As such, epigenetic alterations induced by environmental factors, such as early life adversity and social stress, are found in the brain of humans and rats. In this chapter, we review the evidence in favor of epigenetic factors playing a role in depression and suicide. Animal and human postmortem studies reporting epigenetic alterations in the brain following environmental insults are discussed to generate a global scheme of epigenetic modifications, which are believed to be involved in the pathophysiology of depressive disorders and suicidality.