[Psychological trauma as risk for delayed psychiatric disorders: epigenetic mechanisms]

Psychological trauma is considered to be a risk factor for the development of a number of psychiatric disorders. Although 40-90% of the population is exposed to a traumatic event in their lifetime, only a small fraction of individuals will develop a disorder. In recent years, numerous studies described epigenetic changes, such as DNA methylation, histone modifications and non-coding RNA as potential biological mechanisms by which the environment can have long-term effects on an organism.

This article reviews the accumulating evidence for the involvement of epigenetic factors in the development of psychiatric disorders associated with psychological trauma. Clinically the review focuses on posttraumatic stress disorder (PTSD) for which trauma is a diagnostic criterion. In this context, we specifically focus on studies that show trauma and disease-associated epigenetic changes in humans and animal models. Both tissue-specific as well as cross-tissue effects have been described and underline the global consequences of psychological trauma on the whole organism. In addition, possible epigenetic mechanisms are presented which could be responsible for the long-lasting effects of gene-environment interactions in psychiatric disorders. Finally, the review addresses how a better understanding of these epigenetic mechanisms could suggest avenues for possible future pharmacological and psychotherapeutic treatment approaches.