The Penrose Hypothesis: contradicting evidence from Europe and South America

Abstract

In 1939, Lionel Sharples Penrose, the British mathematician, epidemiologist and psychiatrist published the hypothesis of an inverse relationship between psychiatric bed numbers and prison population rates. He analyzed cross-sectional data from 18 European countries. Recent findings from a longitudinal study in Europe did not support the consistency of the Penrose Hypothesis over the past two decades. We assessed prison population rates and psychiatric bed numbers across six South American countries over the two decades starting in 1991. Panel data regression analyses with country fixed effects were conducted. Reductions of psychiatric bed numbers and the increase in prison population rates were significantly related in South America over the two decades starting in 1991. When and where psychiatric bed numbers reduced more, prison populations increased more. High rates of mental health problems have consistently been reported from Europe and South America. In contrast to Europe, South America showed strong economic growth over the past two decades in a context of high levels of income inequality. Increase of per capita income was also related with increasing prison population rates in South America over the past two decades. However, the relationship between psychiatric bed numbers and prison population rates remained highly significant when controlling for the increase of per capita income and for income inequality.