Prevention of violent behaviors (VB) in the early phase of psychosis (EPP) is a real challenge. Impulsivity was shown to be strongly related to VB, and different evolutions of impulsivity were noticed along treatments. One possible variable involved in the relationship between VB and the evolution of impulsivity is cannabis use (CU). The high prevalence of CU in EPP and its relationship with VB led us to investigate: 1/the impact of CU and 2/the impact of early CU on the evolution of impulsivity levels during a 3-year program, in violent and non-violent EPP patients.

178 non-violent and 62 violent patients (VPs) were followed-up over a 3 year period. Age of onset of CU was assessed at program entry and impulsivity was assessed seven times during the program. The evolution of impulsivity level during the program, as a function of the violent and non-violent groups of patients and CU precocity were analyzed with linear mixed-effects models.

Over the treatment period, impulsivity level did not evolve as a function of the interaction between group and CU (coef. = 0.02, p = 0.425). However, when including precocity of CU, impulsivity was shown to increase significantly only in VPs who start consuming before 15 years of age (coef. = 0.06, p = 0.008).

The precocity of CU in VPs seems to be a key variable of the negative evolution of impulsivity during follow-up and should be closely monitored in EPP patients entering care since they have a higher risk of showing VB.

The correlates of legally significant outcomes that have been identified in people with mental disorders are of limited value in understanding the mechanisms by which these outcomes occur.

To describe the relationships between mental disorder, impaired psychosocial function, and three legally significant outcomes in a representative sample of the US population.

We used a population survey, the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC-III, sample size 36,309), to identify people who self-reported serious trouble with the police or the law over the past 12 months and two lifetime outcomes, being incarcerated and engaging in violence to others. DSM-5 categories were generated using the Alcohol Use Disorder and Associated Disabilities Interview Schedule-5. Psychosocial function was assessed using social and role-emotional function scores of the 12-Item Short-Form Health Survey Version 2.

Participants with mental disorder, but not people with no diagnosis, who reported serious trouble with the police or with the law during the previous 12 months reported significantly worse psychosocial function than those who did not report such trouble. The size of the statistical effect varied by diagnosis, moderate for some forms of mental illness and for alcohol abuse and nonsignificant for drug abuse and the personality disorders. Effect sizes were largest for diagnoses where legally significant outcomes were least common.

The effect of impaired psychosocial function, for instance in disrupting family and social networks that would otherwise protect against these legally significant outcomes, warrants further investigation in studies with longitudinal designs.

Although evidence from psychosis patients demonstrates the adverse effects of cannabis use (CU) at a young age and that the rate of CU is high in subgroups of young violent patients with psychotic disorders, little is known about the possible effect of the age of onset of CU on later violent behaviors (VB). So, we aimed to explore the impact of age at onset of CU on the risk of displaying VB in a cohort of early psychosis patients.

Data were collected prospectively over a 36-month period in the context of an early psychosis cohort study. A total of 265 patients, aged 18–35 years, were included in the study. Logistic regression was performed to assess the link between age of onset of substance use and VB.

Among the 265 patients, 72 had displayed VB and 193 had not. While violent patients began using cannabis on average at age 15.29 (0.45), nonviolent patients had started on average at age 16.97 (0.35) (p = 0.004). Early-onset CU (up to age 15) was a risk factor for VB (odds ratio = 4.47, confidence interval [CI]: 1.13–20.06) when the model was adjusted for age group, other types of substance use, being a user or a nonuser and various violence risk factors and covariates. History of violence and early CU (until 15) were the two main risk factors for VB.

Our results suggest that early-onset CU may play a role in the emergence of VB in early psychosis.

Violent behaviour (VB) occurs in first episode of schizophrenia and can have devastating impact both on victims and patients themselves. A better knowledge of the underlying mechanisms of VB may pave the way to preventive treatments.

1) To explore the nature of the link between impulsivity and VB in early psychosis (EP) patients; 2) To explore the interactions between impulsivity and substance abuse, insight, and positive symptoms, the main dynamic risk factors of VB described to date.

Post hoc analysis of data acquired in the frame of a 36-months EP cohort study. A total of 265 EP patients, aged 18 to 35, treated at TIPP (Treatment and early Intervention in Psychosis Program), at the Department of Psychiatry in Lausanne, Switzerland, were included in the study. Logistic regression analyzes were performed as well as mediation analysis and interaction analysis

Our data suggest that impulsivity is a predictor of VB when analyzed independently and as part of a multi-factorial model. Impulsivity continues to differentiate violent patients from non-violent ones at the end of the program. In addition, the relationship between impulsivity and VB is not mediated by substance abuse. Finally, the effect of impulsivity on the probability of VB is potentiated by the interaction of different levels of insight and positive symptoms.

Early intervention strategies in psychotic disorders should include evaluation of impulsivity considering it is linked to increased risk of VB and may respond to treatment.