Distinct impulsivity profiles in subtypes of violence among community-dwelling patients with severe mental disorders: a longitudinal study

Background: Although only a few patients with severe mental disorders (SMD) can commit violent behaviour in the community, violent behaviour aggravates the stigma towards patients with SMD. Understanding the subtypes of violent behaviour may be beneficial for preventing violent behaviour among patients with SMD, but it has rarely been studied.

Methods: This longitudinal study investigated 1914 patients with SMD in the community at baseline, and the follow-up period ranged from February 2021 to August 2021. The Barratt Impulsiveness Scale Version-11, the Buss-Perry Aggression Questionnaire, the Impulsive/Premeditated Aggression Scale, the Personality Diagnostic Questionnaire and the MacArthur Community Violence Instrument were used at baseline. The Modified Overt Aggression Scale was used to assess the occurrence of violent behaviour (outcome) during the follow-up period. Cox regression models were used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs). Latent class analysis was used to characterise the subtypes of patients with SMD who engaged in violent behaviour at follow-up.

Results: We found that 7.2% of patients with SMD presented violent behaviour within six months in the community. Younger age (OR = 0.98, 95% CI = 0.96-1.00, p = 0.016) and no economic source (OR = 1.60, 95% CI = 1.10-2.33, p = 0.014) were risk factors for violent behaviour. Patients with SMD who engaged in violent behaviour could be classified into three subtypes: one class characterised by a history of violence and impulsivity, another class characterised by high levels of aggression and motor impulsivity, and the last class characterised by median cognitive impulsivity.

Conclusions: Socio-demographic factors were risk factors for violent behaviour among patients with SMD, which could eliminate the discrimination toward this group. Impulsivity played a vital role in identifying the three subtypes of patients with SMD who engaged in violent behaviour. These findings may be helpful for the development of a personalised violence risk management plan for patients with SMD who commit violent behaviour in the community.