Aversive stimulation by staff and violence by psychiatric patients.

This study investigated the frequency with which violence by psychiatric in-patients was preceded by aversive interpersonal stimulation. The precursors of 63 assaults by psychiatric patients on nurses were studied using semi-structured interviews conducted within 72 hours of the assault. Reliability data were collected from staff witnesses and assaultive patients in a subgroup of assaults. Eighty-six per cent of the assaults were immediately preceded by the assaulted nurse having delivered an aversive stimulus to the patient, e.g. frustration, activity demand or physical contact. There were significant associations between diagnosis and the type of aversive stimulation which preceded assaults. Interpersonal factors and diagnosis therefore seem to play a significant role in most violence in psychiatric hospitals and only a minority of patients behave aggressively in the absence of aversive stimulation. An explanation of the link between psychosis and aggressive behaviour in terms of distorted social cognition is discussed.