The prevalence and nature of intellectual disability in Norwegian prisons

The objective of the study was to calculate the prevalence of inmates with intellectual disabilities (ID), and identify historical, medical and criminological characteristics of a certain impact. A random sample of 143 inmates from a Norwegian prison cross sectional sample was studied. The Hayes Ability Screening Index (HASI) was validated with the Wechsler Abbreviated Scale of Intelligence (WASI). The prevalence of inmates with ID, IQ < 70, was 10.8%. Some essential characteristics of inmates with ID were more frequent medication for mental disorders, a higher number of imprisonments, less drug abuse and less education than the other inmates. The results indicated that the HASI is a valid tool for screening of ID for the Norwegian inmates. The prevalence of ID in Norwegian inmates is significant, measured by WASI and HASI. Identification, rehabilitation and care, concerning an intellectual handicap, are mostly absent in the Norwegian criminal justice system.