Evaluating a personalized treatment for substance use disorder in people with mild intellectual disability or borderline intellectual functioning: A study protocol of a multiple baseline across individuals design

BACKGROUND: The prevalence of substance use disorder (SUD) in people with Mild Intellectual Disabilities or Borderline Intellectual Functioning (MID-BIF) is high. However, an effective personalized treatment for people with MID-BIF and SUD is lacking. This paper describes the study protocol of the effectiveness study of Take it Personal!+, a personalized treatment for people with MID-BIF and SUD. METHODS: The effectiveness of Take it Personal!+ in decreasing substance use will be assessed in a non-concurrent multiple baseline across individuals design comprising ten participants with MID-BIF and SUD. The participants with MID-BIF and SUD will be randomly allocated to one of the five baseline lengths (7–11 days). Substance use, will be assessed during baseline, intervention, and post-treatment phase using a daily diary method. DISCUSSION: If this study shows that Take it Personal!+ is effective in decreasing substance use, the gap in treatment for people with MID-BIF and SUD will be filled. TRIAL REGISTRATION: The study is registered in the Netherlands Trial Register (Trial NL4935, registered July 2, 2019).