Childhood Trauma in Psychoses

Psychotic experiences are common in the general population and have been reported in children, adolescents, and adults. Childhood trauma, i.e. maltreatment with the intention to harm, has been proposed to play a causal role in the etiology of psychosis. There is some evidence that this association cannot, at least not solely, be attributed to genetic risk. In other words, childhood trauma increases the risk for later psychopathology independent of genetic risk. Additionally, childhood trauma might mediate the association between genes linked with mechanisms possibly underlying psychosis (such as neuroplasticity and stress regulation) and the onset of psychosis. Another mechanism through which childhood trauma might increase the risk for psychotic symptoms is through its impact on the developing brain. The hippocampus and amygdala are two limbic structures that are densely populated with receptors for stress hormones, which make them particularly sensitive to early life trauma (i.e., early life stress). Main findings include hippocampal volume reductions and increased amygdala reactivity to emotional stimuli. Furthermore, early traumatic experiences may cause heightened sensitivity of the stress response system. For example, studies found that those with a trauma history report more paranoid ideation and subjective stress, even in neutral (social) situations. There is some evidence suggesting a role for the immune system in the association between childhood trauma and psychosis; however, more research needs to be done to unravel “how.” Moreover, there are a number of psychological mechanisms that might explain the association between childhood trauma and psychosis, including feelings of social defeat, cognitive biases, attachment style, and dissociative tendencies. In this chapter, we will review the evidence linking childhood trauma to the onset of psychosis.