The role of early adverse life events in the etiology of depression and posttraumatic stress disorder. Focus on corticotropin-releasing factor.

Abstract

The remarkable progress in neurobiological research techniques has now been applied to investigate the pathogenesis of psychiatric disorders. A large body of literature has confirmed an important biological basis for a majority of severe psychiatric disorders, such as affective and anxiety disorders, including posttraumatic stress disorder (PTSD).' At the beginning of this century, Sigmund Freud's psychoanalytical theory was the major etiological approach for the explanation of psychopathology. According to this theory, conflicts in early life constitute a causal factor for the development of psychological disorders.* In addition to convincing evidence for a genetic contribution in the development of mood and anxiety disorder^,^ evidence for a preeminent role of psychosocial stressors in the pathogenesis of these disorders has also been obtained. For example, episodes of major depression are often preceded by stressful life events6 or are mutually related to episodes of stress.' In a study of identical twins by Kendler et a1.,* lifetime stressors, including childhood abuse and neglect as well as stressful life events in adulthood, were identified as predictors of major depression. In the case of PTSD, a stressful life event outside the range of usual human experiences is required for a diagnosis of the disorder according to DSM-IV criteria.' The inclusion of a stressful event as an etiological factor in the DSM-IV differentiates PTSD from other psychiatric disorders. However, less than one quarter of traumatized individuals subsequently develop syndromal PTSD, suggesting that the disorder does not merely represent a normative reaction to extreme stress.'' Increasing evidence indicates that the Occurrence and persistence of PTSD in response to trauma depends on many factors including other stressful life events- as well as minor psychosocial stressors and daily stressors14 before or after the onset of the traumatic event. Furthermore, recent studies suggest a strong relation between early adverse life events, that is,