Association between neurodevelopmental disorders and recidivism among forensic outpatients under the Medical Treatment and Supervision Act in Japan: A retrospective cohort study.

Aim: Some features of neurodevelopmental disorders (NDDs) have been discussed as potential factors related to criminal behavior, and addressing their characteristics may help prevent recidivism among forensic patients. However, evidence from Japan remains limited. This study examined the association between NDDs and recidivism among forensic outpatients receiving treatment under Japan's Medical Treatment and Supervision Act (MTSA). Methods: This retrospective cohort study used the national database of Japanese forensic outpatients who received treatment under the MTSA between 2005 and 2017. Generalized linear models analyzed the association between NDDs, including intellectual disability (ID), autism spectrum disorder (ASD), and attention deficit hyperactivity disorder (ADHD), and recidivism during outpatient treatment. Results: A total of 2135 patients were included in the analysis, of whom 221 (10.4%) exhibited recidivism. ID, ASD, and ADHD were observed in 10.0%, 3.9%, and 0.3% of patients, respectively. Both ID (adjusted odds ratio [aOR] = 1.92, 95% confidence interval [CI]: 1.29-2.87) and ASD (aOR = 2.94, 95% CI: 1.64-5.27) were associated with an increased risk of recidivism. ID was associated with a higher risk of physical violence (aOR = 2.01, 95% CI: 1.28-3.14) and arson (aOR = 3.43, 95% CI: 1.01-11.71), whereas ASD was associated with physical violence (aOR = 2.87, 95% CI: 1.51-5.46). Conclusion: Among Japanese forensic outpatients, ASD and ID were associated with an increased risk of recidivism during outpatient treatment. These findings highlight the importance of developing tailored support and multidisciplinary interventions that address the specific needs of individuals with NDDs.