LAUSR

Abstract People with an intellectual disability (ID) make up an unknown proportion of those seeking substance use treatment. We reviewed existing evidence on prevalence estimates relating to tobacco use, drug and alcohol use, and misuse in ID. Ten electronic databases were searched to identify studies published 1980 to 2016 describing substance use and misuse prevalence estimates in ID. 39 studies were identified (UK, 13; US, 10; Australia, 4; Netherlands, 3; Sweden, 2; Belgium, 1; Finland, 1; India, 1; Ireland, 1; Serbia, 1; more than 1 country, 2). The review highlighted considerable methodological variance in the description and diagnosis of ID plus substantial between-study variation in how use, misuse, and dependency were defined. Current alcohol use prevalence ranged from 1.9% to 55%; current tobacco use prevalence from 0% to 62.9%; and current cannabis use prevalence from 5% to 9.5%. The prevalence of substance use and misuse in ID is highly variable; studies included in this review were too heterogeneous to determine conclusively whether prevalence rates are higher, lower, or equivalent in ID versus non-ID samples. The use of substances amongst people with ID requires greater consideration by researchers, service providers, and commissioners.