The Penrose hypothesis in the second half of the 20th century: investigating the relationship between psychiatric bed numbers and the prison population in England between 1960 and 2018–2019

Abstract

Background NHS Psychiatric beds comprise mental illness and intellectual disability beds. Penrose hypothesised that the number of psychiatric in-patients was inversely related to prison population size. Aims To ascertain whether the Penrose hypothesis held true in England between 1960 and 2018–2019. Method A time-series analysis explored the association between total prison population and NHS psychiatric beds; this was also tested for the male and female prison populations, using non-psychiatric beds as a comparator. Associations were explored with time lags of up to 20 years. Linear regression was conducted to estimate the size of the effect of bed closures. Results NHS psychiatric beds decreased 93% and the prison population increased 208%. A strong (r =−0.96) and highly significant negative correlation between these changes was found. Annual reduction in psychiatric bed numbers was associated with an increase in prison population, strongest at a lag of 10 years. The closure of mental illness and intellectual disability beds was associated with increases in female prisoners 10 years later. The only significant explanatory variable for the increase in male prison population was intellectual disability bed reduction. Conclusions The Penrose hypothesis held true between 1960 and 2018–2019 in England: psychiatric bed closures were associated with increases in prison population up to 10 years later. For every 100 psychiatric beds closed, there were 36 more prisoners 10 years later: 3 more female prisoners and 33 more male prisoners. Our results suggest that the dramatic increase in the female prison population may relate to the closure of NHS beds.

The potential unintended consequences of Mental Health Act reforms in England and Wales on people with intellectual disability and/or autism

“…Annual reduction in psychiatric bed numbers has been reported to be associated with an increase in the prison population. 4 Although not specific to people with ID/A, this risk of ‘trans-institutionalisation’ is a potential concern.…”

I Refuse for the Devil to Take My Soul: Inside Cook County JailLiliKobielski by powerHouse Book, 2018. 152 pages, ISBN13: 9781576878880

“…A 2015 study found it to be inapplicable to the European situation at the time (Bluml et al, 2015). Such simple relationships are rarely satisfactory without significant explication, and much research and commentary have amassed on the topic in recent decades (Kalapos, 2016; Lamb, 2015; Prins, 2011; Wild et al, 2022).…”

Beyond the Penrose Hypothesis: Examining the Association between the Availability of Psychiatric Care and National Homicide Rates in 166 Countries

“…In the eight decades since Penrose's initial observations and proposal, several researchers have examined the evidence for the Penrose hypothesis at the national and cross-national levels. Studies from the United Kingdom [14] and Hungary [13] have both reported significant negative correlations between the number of psychiatric beds and the prison population; in both these countries, a reduction in the number of psychiatric beds was associated with an increase in the prison population over time. However, the Hungarian data suggested that this association was confined to the prison population alone; there was no corresponding relationship between the number of psychiatric beds and the crime rate [13].…”

“…This has subsequently been referred to in the literature as the "Penrose hypothesis" [11], "Penrose effect" [12] or "Penrose's law" [13]. Penrose's original proposal included both "insanity" (which would be termed "severe mental illness" or "psychosis" today) and "intellectual insufficiency" (now named "intellectual disability") as relevant diagnosis, and he also considered the possibility of a gender difference in this association [10,14]. The Penrose hypothesis essentially implies that the availability of in-patient psychiatric case may reduce the rates of incarceration in those whose criminal offences were related to mental illness.…”