Does substance use predict contact with the criminal justice system for people with intellectual disabilities?

The purpose of this paper is to examine how substances misuse impacts on exposure to the criminal justice system for people with intellectual disabilities (ID).

An electronic case-register of mental health patients was used to examine the clinical records of 411 patients with ID. χ2 analysis was performed to test the association between variables and logistic regression to generate estimates for statistically significant association variables.

Of 411 cases, 98 (23 per cent) of patient had a history of substance use, with affective disorders strongly associated with alcohol misuse χ2=4.135, df=1 (p<0.042), similarly statistically significant predictor for alcohol misuse OR: 1.7, 95 per cent CI (1.02-2.72) (p<0.043). Patients with a history of offending behaviour had three-folds higher risk to misuse drugs compared to those without a forensic conviction OR: 3.17, 95 per cent CI (1.35-7.44) (p<0.008). Those with a history of offending were more likely to have had a history of substance use.

Substance use and its impact on offending by people with ID is still poorly understood. This paper adds new information to this under researched area.