Substance Use in Individuals with Mild to Borderline Intellectual Disability: an Exploration of Rates and Risks in the Netherlands

Little is known about rates and risk factors of substance use (SU) in individuals with mild to borderline intellectual disabilities (MBID, IQ 50–85). This hinders targeted prevention and treatment. In this study we assessed SU rates and risk factors in individuals with MBID in 419 adults (63% male, average IQ = 66) in 16 Dutch disability services. Lifetime and current SU, SU picture recognition, knowledge, attitudes and modeling were assessed with the Substance use and misuse in Intellectual Disability - Questionnaire (SumID-Q). Lifetime licit SU (alcohol and tobacco) was 97%, lifetime illicit SU (predominantly cannabis) was 50%. Current users of tobacco (62%), alcohol (64%), and cannabis (15%) initiated SU at a younger age than those who desisted SU (ps < .001). Participants with mild ID and those with borderline ID did not differ in SU rates (ps .429–.812), or age at SU initiation (ps .221–.853). Current licit SU and lifetime illicit SU were related to male gender, younger age, and (for smoking and stimulant use) to lack of daytime activities. However, these factors did not contribute to multivariate models when recognition, knowledge, attitudes and modeling were added. The models correctly identified current SU in 84% (smoking) and 74% (drinking), and lifetime SU in 76% (cannabis) and 84% (stimulants) of the participants. As almost all participants reported lifetime use of licit, and about half reported lifetime illicit substance use, systematic screening for substance use, and development of preventative and treatment interventions targeted to this group are needed

Substance use in individuals with mild to borderline intellectual disability:A comparison between self-report, collateral-report and biomarker analysis

Background and aims Individuals with mild or borderline intellectual disability (MBID) are at risk of substance use (SU). At present, it is unclear which strategy is the best for assessing SU in individuals with MBID. This study compares three strategies, namely self-report, collateral-report, and biomarker analysis. Methods and procedures In a sample of 112 participants with MBID from six Dutch facilities providing care to individuals with intellectual disabilities, willingness to participate, SU rates, and agreement between the three strategies were explored. The Substance use and misuse in Intellectual Disability − Questionnaire (SumID-Q; self-report) assesses lifetime use, use in the previous month, and recent use of tobacco, alcohol, cannabis, and stimulants. The Substance use and misuse in Intellectual Disability − Collateral-report questionnaire (SumID-CR; collateral-report) assesses staff members' report of participants' SU over the same reference periods as the SumID-Q. Biomarkers for SU, such as cotinine (metabolite of nicotine), ethanol, tetrahydrocannabinol (THC), and its metabolite THCCOOH, benzoylecgonine (metabolite of cocaine), and amphetamines were assessed in urine, hair, and sweat patches. Results Willingness to provide biomarker samples was significantly lower compared to willingness to complete the SumID-Q (p < 0.001). Most participants reported smoking, drinking alcohol, and using cannabis at least once in their lives, and about a fifth had ever used stimulants. Collateralreported lifetime use was significantly lower. However, self-reported past month and recent SU rates did not differ significantly from the rates from collateral-reports or biomarkers, with the exception of lower alcohol use rates found in biomarker analysis. The agreement between self-report and biomarker analysis was substantial (kappas 0.60–0.89), except for alcohol use (kappa 0.06). Disagreement between SumID-Q and biomarkers concerned mainly over-reporting of the SumID-Q. The agreement between SumID-CR and biomarker analysis was moderate to substantial (kappas 0.48 − 0.88), again with the exception of alcohol (kappa 0.02). Conclusions and implications In this study, the three strategies that were used to assess SU in individuals with MBID differed significantly in participation rates, but not in SU rates. Several explanations for the better-than-expected performance of self- and collateral-reports are presented. We conclude that for individuals with MBID, self-report combined with collateralreport can be used to assess current SU, and this combination may contribute to collaborative, early intervention efforts to reduce SU and its related harms in this vulnerable group