Substance Use Disorder among People with Intellectual and Developmental Disabilities: A Narrative Review

Context: People with intellectual and developmental disabilities (IDD) are a vulnerable and growing population. Research on substance use disorder (SUD) among people with IDD is limited, and there are gaps in knowledge for areas such as prevention and treatment of SUD for people with IDD. The extant literature suggests that people with IDD are less likely to use substances overall compared to people without a disability; however, they tend to be more susceptible to SUD if they do use substances.

Objective: to better understand the relationship between IDD and SUD, and identify the best practices to improve adherence to treatment and improve health outcomes in this high-risk group

Study Design: Narrative review

Setting or Dataset: review of the literature using the following databases: CINAHL, Pubmed, Scopus, Web of Science, Academic Search Complete, and PsychINFO

Population studied: English peer-reviewed sources published between January 1, 2000–December 31, 2020

Outcome Measures: co-occurrence of SUD and IDD, risk factors common to IDD and SUD, treatment options for adults with SUD and IDD, and barriers to receiving or adhering to treatment for adults with IDD.

Results: Generally, the prevalence of substance use among adults with IDD appears to be lower than adults without IDD. However, research suggests that people with IDD who do use substances are at elevated risk of developing a SUD. Individuals with IDD and SUD are most commonly encountered in outpatient mental health settings. Cannabis, alcohol, and cocaine use disorders are the most frequent substances used by people with IDD. Risk factors for SUD among individuals with IDD include being male, having a family history of SUD, being exposed to peers who use substances, having psychiatric comorbidities, and having mild/borderline IDD. Estimates of co-occurring psychiatric disorders for those with IDD and SUD range from 42% to 54%. Treatment staff who provide SUD are not trained to work with clients with IDD.

Conclusion: Factors that would improve outcomes for individuals with IDD and SUD include evidence-based training for treatment providers as well as individualized care that accounts for risk factors, co-morbid mental health diagnoses, and substance used. The lack of a shared universal language may impede the understanding and dissemination of research and reporting for people with IDD.