Patients with first-episode psychosis are more likely to report being involved in violence over subsequent years if they persist with illicit drug use, a 10-year study shows.
The rate of arrest or imprisonment for violent offences fell over the study period, with 19 (11%) of 178 patients reporting this in the year before baseline, compared with just 2% in the year before the 10-year follow-up assessment. In line with other recent research, this suggests that antipsychotic treatment reduces violent crime in patients with psychosis, says the research team.
Lead researcher Johannes Langeveld (Stavanger University Hospital, Norway) and colleagues note that schizophrenia is traditionally associated with violent behaviour. “For the majority of individuals with psychosis, this stereotype is clearly wrong”, they write in Schizophrenia Research.
“At ten years following their initial contact with mental health services, psychotic patients are not more dangerous than the general population, as long as they are not using illegal drugs.”
The patients in the study reported their involvement with violence on a questionnaire during follow-up. Besides the 2% arrested or imprisoned at the 10-year follow-up, 15% reported initiating or becoming involved in threatening or physically violent behaviour.
Patients involved in threatening or physically violent behaviour at 10 years were more likely than other patients to use illegal drugs at baseline (43 vs 19%), after 5 years (32 vs 11%) and at 10 years (36 vs 10%). And on multivariate analysis, illegal drug use increased the risk of violence more than threefold.
Violent patients were as likely as nonviolent patients to be receiving antipsychotic treatment. But despite this, they had more positive, cognitive and excitative psychosis symptoms, had a longer cumulative duration of untreated psychosis between the 5- and 10-year follow-up points and were less likely to be in remission, although only this latter factor remained significant in multivariate analysis.
“Consequently, more assertive treatment throughout the follow-up period might have further reduced the rate of violence”, the researchers speculate, especially if combined with attempts to reduce illegal drug use.
Of note, violent patients actually spent more time than nonviolent patients in hospital during follow-up, at 21.2% versus 5.9% of the period between the 5- and 10-year follow-up assessments.
“Thus, although these subjects had fewer opportunities to commit violent behavior, they engaged in more violent behavior”, says the team.