A comparison of trajectories of offending among people with psychotic disorders, other mental disorders and no mental disorders: Evidence from a whole-of-population birth cohort study.

BACKGROUND: Trajectory analysis has been used to study long-term offending patterns and identify offender subgroups, but few such studies have included people with psychotic disorders (PDs) and these have been restricted to adult offenders. AIMS: To compare offending trajectories among 10-26-year-olds with PDs with those with other mental disorders (OMDs) or none (NMD) and identify associated risk factors. METHODS: This is a record-linkage study of 184,147 people born in Western Australia (WA) 1983-1991, drawing on data from WA mental health information system, WA corrective services and other state-wide registers. Group-based trajectory modelling was used to identify offending trajectories. RESULTS: Four offender groups were identified in each mental health status group: G1-no/negligible offending; G2-early onset, adolescent, desisting by age 18; G3-early onset, low rate, offending into early adulthood; and G4-very early onset, high rate, peaking at age 17, continuing into early adulthood. The PDs group had the lowest proportion of individuals with no or negligible offending histories-84% compared with 88.5% in the OMDs group and 96.6% in the no mental disorder group. Within mental health status offender groups, the PDs group was characterised by early or very early onset offending persisting into adulthood, accounting for 5.4% and 3.7% of the group respectively (OMD: 3.8%, 1.5%; NMD: 1.0%, 0.5%). Gender, indigenous status, substance use problems, childhood abuse and parental offending were generally associated with trajectory group membership, although among those with PDs childhood abuse and parental offending were only significant in the early onset-life-course-persistent group. CONCLUSIONS: While most people with PDs never offend, some are disproportionately vulnerable from a particularly early age. If the offending subgroup is to be helped away from criminal justice involvement, interventions must be considered in childhood.

Impact of social disadvantage and parental offending on rates of criminal offending among offspring of women with severe mental illness.

OBJECTIVE: Children of parents with severe mental illness have an increased risk of offending. Studies suggest that risk factors such as parental offending and social disadvantage may be associated with the increased risk. This paper assesses the impact of these risk factors on offending rates in the offspring of women with severe mental illness compared to offspring of unaffected women. METHODS: This is part of a longitudinal record-linked whole-population study of 467,945 children born in Western Australia from 1980 to 2001 to mothers with severe mental illness and mothers with no recorded psychiatric illness. These data were linked to Western Australia corrective services data producing a dataset of 12,999 people with at least one offence (3.7% of birth cohort). Cox proportional hazard was used to calculate incidence rate ratios of offspring offending. RESULTS: The offending rate for offspring of mothers with severe mental illness (cases) was almost three times the rate for offspring of unaffected mothers (comparison) with an unadjusted incidence rate ratio of 2.75 (95% confidence interval: [2.58, 2.93]). Adjusting for sex, indigenous status, socio-economic status and geographical remoteness reduced the rate ratio by 24% to incidence rate ratio 2.10, 95% confidence interval: [1.97, 2.23]. Adjusting for parental offending further reduced the rate ratio by 23% to incidence rate ratio 1.62, 95% confidence interval: [1.52, 1.72]. The mean age at first recorded offence was significantly lower for cases compared to comparison offspring. CONCLUSION: Children of mothers with a severe mental illness have a higher rate of offending than children of unaffected mothers, and social disadvantage and parental offending have a major impact on this rate. Services supporting these vulnerable children need to focus on improving the social environment in which they and their families live in.