Short-term effects of psychiatric symptoms and interpersonal stressors on criminal violence--a case-crossover study

The aim of the study was to analyse the triggering or acute risk effect of psychiatric symptoms and interpersonal stressors on criminal violence.

One hundred and thirty three violent offenders were recruited from a forensic psychiatric evaluation (FPE) unit and a national prison evaluation unit in Sweden during 2002-2003, and were interviewed about trigger exposures. A case-crossover design was used eliminating long-term within individual confounding.

Suicidal ideation or parasuicide within 24 h before the violent event conferred a ninefold risk increase. In contrast, violent ideation did not trigger criminal violence. Hallucinations yielded a fourfold risk increase, whereas paranoid thoughts were associated with a small and statistically non-significant risk increase. Acute conflicts with others and being denied psychiatric care within 24 h before violence also increased the risk of acting violently.

Some tested psychiatric symptoms and stressors triggered criminal violence, whereas others did not. The case-crossover design may be particularly useful for the study of triggers of violence.