Potential transgenerational epigenetic effects of prolonged stress and psychological trauma

Exposure to psychological trauma is a strong risk factor for several debilitating disorders including posttraumatic stress disorder (PTSD) and depression. Besides the impact on mental well-being and behavior in the exposed individuals, it has been suggested that psychological trauma can affect the biology of the individuals and may even have biological and behavioral consequences on the offspring of exposed individuals. While knowledge of possible epigenetic underpinnings of the association between exposure to trauma and risk of PTSD has been discussed in several reviews, it remains to be established whether or not trauma-induced epigenetic modifications can be passed from traumatized individuals to subsequent generations of offspring. The aim of this chapter is to review the emerging literature on the evidence of transgenerational inheritance due to trauma exposure on the epigenetic mechanism of DNA methylation in humans. Our data presented in this chapter suggests an accumulating evidence that the effect of trauma exposure can be passed down to offspring transgenerationally, which has the capacity to change the expression of genes and the metabolome. The epigenetic inheritance mechanism studied so far in this area is DNA methylation. This chapter summarizes and critically reviews the relevant original human studies in this area. Thus it provides an overview of where we stand, and a clearer vision of where we should go in terms of future research directions.