Objective: To evaluate the individual- and population-level impact of a combination of factors, including traumatic brain injury (TBI) and certain maternal characteristics, on subsequent criminal conviction.
Design and participants: A retrospective record linkage study involving a cohort of 30 599 individuals born between 1980 and 1985, with ratio of 1 (with TBI): 3 (no TBI), matched by sex and the year of birth.
Methods and procedures: Cox proportional hazard regression models and population attributable risk percentages (PAR%) were used to assess the contribution of TBI and other risk factors on subsequent criminal convictions.
Main outcomes and results: Overall, individuals born to the teenaged mothers (<20 years) have significantly higher proportion of TBI than those born to older mothers (35% vs 22%; P < .001). In the gender-specific analyses, a history of TBI was associated with increased risk for criminal convictions (adjusted hazard ratio [aHR]: 1.48, 95% confidence interval [CI]: 1.36-1.60, and aHR: 1.45, 95% CI: 1.22-1.73, for men and women, respectively). Maternal characteristics (maternal age, single parent, multiparity) were identified as the greater contributor to the criminal convictions (PAR%: 57% and 67% for men and women, respectively). The combined impact of mental illness, maternal factors, and TBI was estimated to be 67% and 74% (for men and women, respectively); with nonoverlapping 95% CIs for PAR%, these factors were estimated to have had a higher impact among females than among males.
Conclusion: More than half of the criminal convictions were associated with a relatively small number of risk factors, including poor mental health, low socioeconomic status, and TBI as well as certain maternal characteristics.