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
Dr Giulietta Valuri1, Adj/A/Prof Frank Morgan1, Dr Anna Ferrante2, Dr Assen Jablensky3, W/Prof Vera Morgan1
1School of Population and Global Health, University of Western Australia, Perth, Australia
2Curtin University, Perth, Australia
3Division of Psychiatry, University of Western Australia, Perth, Australia
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 and those that have, have been restricted to adult offenders.
Aims: To compare offending trajectories among 10-26 year olds with psychotic disorders (PD) with those for people with other mental disorders (OMD) and people with no mental disorders (NMD), and to 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 PD group had the lowest proportion of individuals with no or negligible offending histories – 84% compared with 88.5% in the OMD group and 96.6% in the NMD group. Within mental health status offender groups, the PD 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 PD, childhood abuse and parental offending were only significant in the early onset-life-course-persistent group.
Conclusions: While most people with PD never offend, some are disproportionately vulnerable from a particularly early age. If the offending subgroup is to be diverted from criminal justice involvement, interventions must be considered in childhood.
Giulietta is a computer programmer/data analyst and epidemiologist who has worked in injury prevention research and with linked WA population databases in both criminology (patterns of offending) and mental health. One of her main roles is to develop and maintain databases that house these linked data. Her research has included: studying patterns of offending in people with a mental illness, measuring and mapping children’s health status using WA data from linked statewide health registers and constructing offending profiles for these children using criminal offending data. Her expertise is in linked data research, database design, programming and management, and analytical techniques.