In recent years, there has been a growing awareness of the importance of abuse or trauma in shaping the course of people's lives. There is growing literature to indicate that trauma is also linked with more severe psychiatric disturbances, including symptoms indicative of psychosis in general and schizophrenia in particular. Several lines of evidence suggest an association between trauma and psychosis with a dose-response effect. First, studies have demonstrated a high incidence of trauma in the lifetimes of patients with psychosis. Abused patients are particularly likely to experience positive symptoms, such as paranoid ideation, thought insertion, visual hallucinations, ideas of reading someone else's mind, ideas of reference, and hearing voices making comments. Secondly, it has been suggested that of all diagnostic categories, psychosis displays the strongest association with child abuse. Thirdly, according to some researchers childhood sexual abuse is the most powerful predictor of later psychiatric symptoms and disorders after controlling for significant demographic variables.
It has been suggested that the experience of abuse may create a biological or psychological vulnerability for the development of psychotic symptoms, including sub-clinical psychotic experiences such as low-grade delusional ideation, suicidal thinking and isolated auditory hallucinations. Exposure to psychological trauma worsens the prognosis of expression of psychosis, in terms of greater likelihood of transition to a more severe psychotic state. According to recent cognitive models of psychosis early adverse experiences such as social marginalization, childhood loss or severe childhood trauma may create an enduring cognitive vulnerability characterized by less subjective control over these experiences, negative schematic models of the self and a world that facilitates external attributions. This tendency to externally attribute events may lie beneath paranoid ideation.
Current ideas about biological consequences of early adversities lend even more credibility to the notion of an enduring psychological vulnerability. It has been suggested that adverse life events or significant losses might be able to mould the neurodevelopmental abnormalities that underlie sensitivity to stressors, if they occur early enough or are sufficiently severe. Thus abnormal neurodevelopmental processes may originate from traumatic events in childhood. Specifically, when exposure to stressors persists and heightened stress-induced glucocorticoid release is chronic, permanent changes in the hypothalamic-pituitary-adrenal (HPA) axis may ensue. This may account for the dopaminergic abnormalities considered central to biological accounts of psychosis. Other researchers are also examining the role of dissociative processes, attachment styles, and trauma related cognitive biases to try to better understand precisely how childhood trauma can lead to psychosis later in life.
Clinically it is imperative to routinely enquire about traumatic experiences to respond appropriately and to offer psychosocial treatments to those who report traumatic life events in the context of psychotic experiences.