Mental health disorders and risk of solitary confinement among incarcerated individuals: a nationwide longitudinal cohort study from Norway.

BACKGROUND: Solitary confinement is extensively used in prisons, constituting a risk of deteriorating health. However, its associations with mental health disorders remain unclear. OBJECTIVE: To investigate the association between history of diagnosed mental health disorders and solitary confinement among incarcerated individuals. METHODS: We included 35 210 individuals with 51 502 incarcerations in Norway from 2015 to 2022 in the Norwegian Prison Release study (nPRIS), linking national prison, health, mortality and demographic registries. Mental health disorders diagnosed within 5 years before incarceration were identified. The primary outcome was solitary confinement and four subtypes: court decided, disciplinary, self-requested and security cell. By analysing all incarcerations, we estimated adjusted ORs (aORs) and rate ratios (RRs) with logistic and negative binomial regression, using robust SEs to account for individual-level clustering across multiple incarcerations. FINDINGS: Among all individuals with a 5-year history of diagnosed mental health disorders (n=18 315), 30.8% experienced solitary confinement, compared with 21.3% among those without a diagnosis (n=16 895). Mental health disorders were associated with higher odds of any solitary confinement (aOR 1.77, 95% CI 1.68 to 1.85) and security cell placement (aOR 4.28, 95% CI 3.57 to 5.13). People with mental health disorders also had a higher rate of disciplinary (adjusted rate ratio (aRR) 3.84, 95% CI 3.41 to 4.33) and self-requested (aRR 2.46, 95% CI 1.91 to 3.18) solitary confinement days. Substance use disorders, severe mental illness and multimorbidity were associated with a higher rate of solitary confinement days, while mental health disorders were inversely associated with court decided solitary confinement (aOR 0.52, 95% CI 0.47 to 0.57; aRR 0.48, 95% CI 0.41 to 0.57). CONCLUSION: People with a history of diagnosed mental health disorders disproportionately experience solitary confinement in prison, risking further deterioration of health. CLINICAL IMPLICATIONS: Health authorities and correctional services should reduce solitary confinement and develop alternative, health-protective segregation strategies for people with mental health disorders.