Introduction: In a comprehensive search of published studies of homicide during psychotic illness, we found 16 studies that specified whether the patients had received treatment before their offence (Nielssen and Large, 2007). Of these, nine provided sufficient information to enable us to estimate the risk of homicide in first onset psychosis (FEP) and previously treated psychosis (PTP) using established values for the incidence and prevalence of FEP and schizophrenia. On average the risk of committing homicide during the first episode of psychosis was one in 576 new cases and the average risk of homicide in previously treated psychosis (PTP) was one in 7400 patients per annum.
Objective: To establish whether there is an association between delays in treatment of psychotic illness and psychotic homicide.
Method: The results of systematic searches of published studies of homicide in first episode psychosis and duration of untreated psychosis were combined to examine the relationship between delayed treatment and the incidence of psychotic homicide.
Key findings: A high proportion of homicides take place in the first episode of psychotic illness (FEP). There are a higher proportion of homicides by patients in their first episodes of illness in countries where longer durations of untreated psychosis (DUP) have been reported. The overall rate of psychotic homicide appears to be lower in countries with shorter DUP. Finally, the risk of homicide by patients with previously treated psychosis (PTP) is lower than had been reported.
Conclusions: Reducing the duration of untreated psychosis would reduce the rate of homicides by a largest group of mentally abnormal offenders, those in their first episode of psychotic illness. We believe reducing the duration of untreated psychosis would save lives and should be an explicit aim of all mental health services.
