From adversity to psychosis: pathways and mechanisms from specific adversities to specific symptoms

Purpose
Although there is considerable evidence that adversities in childhood such as social deprivation, sexual abuse, separation from parents, neglect and exposure to deviant parental communication are associated with psychosis in later life, most studies have considered broad diagnoses as outcomes. In this review we consider evidence for pathways between specific types of adversity and specific symptoms of psychosis.

Methods
We present theoretical arguments for expecting some degree of specificity (although by no means perfect specificity) between different kinds of adversity and different symptoms of psychosis. We review studies that have investigated social–environmental risk factors for thought disorder, auditory–verbal hallucinations and paranoid delusions, and consider how these risk factors may impact on specific psychological and biological mechanisms.

Results
Communication deviance in parents has been implicated in the development of thought disorder in offspring, childhood sexual abuse has been particularly implicated in auditory–verbal hallucinations, and attachment-disrupting events (e.g. neglect, being brought up in an institution) may have particular potency for the development of paranoid symptoms. Current research on psychological mechanisms underlying these symptoms suggests a number of symptom-specific mechanisms that may explain these associations.

Conclusions
Few studies have considered symptoms, underlying mechanisms and different kinds of adversity at the same time. Future research along these lines will have the potential to elucidate the mechanisms that lead to severe mental illness, and may have considerable clinical implications.