Timing, frequency, and duration of incarceration and their impact on mental illness: Evidence from an Australian birth cohort

Purpose

Incarceration is linked to mental illness (MI), but limited evidence exists on the impact of the timing, duration, and frequency of incarceration on the mental health of males and females.

Methods

Data were drawn from a cohort of 83,049 people registered as born in Queensland in 1983/84 and followed to age 29–31 years. Cox regression analyses were conducted to predict the risk of MI diagnosis post-incarceration (youth detention or adult prison).

Results

There were 2010 individuals with a record of imprisonment/detention, of which 46.4% also had MI. Incarcerated males had a longer median time to first MI diagnosis post-custody than incarcerated females (4.6 vs 3.0 years). Incarcerated males who were Indigenous, first offended at an early age, were incarcerated more than once, and had a history of violent offences had an increased likelihood of first MI diagnosis post-custody. However, for females, incarceration-related variables were not predictive of first MI diagnosis post-custody. This might be due to the small number of incarcerated females, with a high proportion of them receiving MI diagnoses prior to prison/detention (65.3%).

Conclusions

This study expands existing evidence by providing comprehensive and detailed insight into the association between incarceration and MI for males and females.