Substance use disorders (SUD) are common in adults with ADHD. A co-occurring ADHD diagnosis is associated with poorer treatment outcomes for both the ADHD and the SUD and higher rates of relapse to substance use.

To explore the relationship between ADHD and SUD longitudinally to identify factors to help improve treatment outcomes.

Prevalence of ADHD symptoms was investigated in a national cohort of SUD patients one year after SUD treatment initiation. Factors at baseline related to ADHD symptoms were explored at follow up.

Five hundred and forty-eight individuals were interviewed in a multi-center study involving 21 treatment facilities at treatment initiation and one year later (n = 261). ADHD symptoms were measured by the Adult ADHD Self Report Scale (ASRS-v.1-1) at follow-up. Individuals who screened positively for ADHD (ADHD + ) were compared to those who screened negatively on baseline variables. Emotional distress was measured by Hopkin's Symptom Check List-25.

At follow-up 35% screened positively for ADHD. In bivariate analysis the ADHD+ group was older, was less likely to have children, reported lower educational level, had more frequent use of stimulants, cannabis and benzodiazepines, and experienced higher degree of emotional stress. When controlling for other significant variables in a logistic regression analysis, the ADHD+ group was associated with more frequent use of cannabis (OR 2.14; CI 1.08–4.23) and of higher psychiatric symptom burden (OR 1.79; CI 1.22–2.61).

A high prevalence of ADHD symptoms and associated challenges underline the importance of systematic screening of individuals entering SUD treatment.

The authors have not supplied their declaration of competing interest.