From the stressed adolescent to the anxious and depressed adult: Investigations in rodent models

Anxiety and depression are the most prevalent of the psychiatric disorders. The average age of onset of these disorders is in adolescence, and stressful experiences are recognized as an important pathway to such dysfunction. Until recently, however, most animal models of these disorders involved adult males. We provide a brief overview of anxiety and depression and the extent to which adolescent rodents are a valid model for their investigation, and briefly review the main measures of anxiety-like and depressive behaviour in rodents. The focus of the review is investigations in which adolescent rodents were exposed to chronic stressors, describing our research using social instability stress and that of other researchers using various social and non-social stressors. The evidence to date suggests stress in adolescence alters the trajectory of brain development, and particularly that of the hippocampus, increasing anxiety and depressive behaviour in adulthood.

► Overview of anxiety and depressive disorders in adolescent humans. ► Overview of animal models of anxiety and depression. ► Review lasting effects of social and non-social stressors in adolescent rodents. ► Stress in adolescence increases anxiety-like and depressive behaviour in adulthood. ► Altered hippocampal development may underlie effects of stressors in adolescence.