A 25-year dynamic ecological analysis of psychiatric hospital admissions and prison committals: Penrose's hypothesis updated.

Penrose's hypothesis applies to admissions to psychiatric hospitals and prisons in Ireland over time (dynamic measures), just as it does to the numbers of places in psychiatric hospitals and prisons in Ireland and elsewhere (static, cross-sectional measures). Although no causal connection can be definitively established yet, mentally disordered prisoners are usually known to community mental health services. Psychiatric services for prisons and the community should be linked to ensure that the needs of those currently accessing care through prisons can also be met in the community.