Discontinuation and reinitiation of pharmacological treatment for ADHD among individuals with ADHD and substance use disorder

Background Attention-deficit/hyperactivity disorder (ADHD) and substance use disorder (SUD) often coexist. ADHD complicates the course of disease in SUD. While recommended in guidelines, ADHD medication for those with comorbid SUD remains controversial. Objective This study aims to explore how comorbid SUD affects ADHD medication discontinuation and reinitiation in individuals with ADHD. Methods Using a matched cohort design, we identified 9283 individuals with ADHD and SUD in Sweden between 2006 and 2020, who had ongoing ADHD medication at the time of their first SUD-related event. Controls with ADHD medication but no SUD (n=46 401) were matched 5:1 on sex and birth year. HRs for treatment discontinuation within 1 year from first SUD, and for treatment reinitiation within 1 year from the first discontinuation, were estimated using stratified Cox models. Findings Individuals with ADHD and SUD were nearly two times as likely to discontinue ADHD treatment within 1 year (HR: 1.99, 95% CI 1.92 to 2.07) and less likely to re-initiate ADHD treatment (HR: 0.82, 95% CI 0.76 to 0.89) compared with controls. Several factors, including male sex, adolescent to young adult age and lower stimulant medication dose, were associated with increased risk for treatment discontinuation, but only adolescent to young adult age was significantly associated with treatment reinitiation in those with ADHD and SUD. Conclusions The results suggest less treatment continuity and access for those with ADHD and comorbid SUD. Clinical implications Treatment providers need to consider the specific needs of individuals with ADHD and comorbid SUD, especially in young males, to improve treatment outcomes for vulnerable groups.