Understanding the Long-Term Clinical Course of Comorbid SUD and ADHD

Comorbid SUD and ADHD is associated with more severe illness. What do we understand about these comorbid conditions and what do we still need to learn?

While substance use disorders (SUDs) often cooccur with attention-deficit/hyperactivity disorder (ADHD), little is known about the long-term clinical course of patients with comorbid SUD and ADHD.

The International Naturalistic Cohort Study of ADHD and SUD (INCAS) is a prospective observational cohort study of treatment-seeking individuals with SUD and comorbid adult ADHD and was designed to examine the clinical course in different treatment settings and countries. Investigators detailed treatment modalities; how age, gender, primary substance of abuse, and other psychiatric comorbidities affected treatment outcomes; and longitudinal data on a broad range of psychological measures, like cognitive symptoms.1

Participants included adult patients with comorbid SUD and ADHD seeking treatment and were recruited from 12 study sites in 9 different countries. From June 2017-May 2021, 578 participants were enrolled, 137 females and 441 males. The sample’s mean age was 36.7 years. At baseline, the most prevalent SUDs were with alcohol (54.2%), stimulants (43.6%), cannabis (33.1%), and opioids (14.5%). Some participants reported previous treatment for SUD (71.1%) and ADHD (56.9%). Other comorbid mental disorders included major depression (31.5%), posttraumatic stress disorder (12.1%), and borderline personality disorder (10.2%).

“This study will provide information on potential predictors for successful treatment outcomes for different treatment modalities and thus hypotheses for future randomized controlled trials,” wrote the study’s authors.1

Previous research has shown that SUD with comorbid ADHD, compared to SUD alone, is associated with more severe and complex illness, including earlier onset of substance use,2,3 a higher degree of use of multiple substances,3,4 more psychiatric comorbidity,5 chronicity,3,4 and poorer SUD treatment outcomes.4,6,7

“Data show that many SUD patients with comorbid ADHD had never received treatment for their ADHD prior to enrolment in the study. Future reports on this study will identify the course and potential predictors for successful pharmaceutical and psychological treatment outcomes,” concluded the authors.1


1. Brynte C, Aeschlimann M, Barta C, et al. The clinical course of comorbid substance use disorder and attention deficit/hyperactivity disorder: protocol and clinical characteristics of the INCAS study. BMC Psychiatry. 2022;22:625.

2. Kaye S, Ramos-Quiroga JA, van de Glind G, et al. Persistence and subtype stability of ADHD among substance use disorder treatment seekers. J Atten Disord. 2019;23(12):1438-1453.

3. Fatseas M, Hurmic H, Serre F, et al. Addiction severity pattern associated with adult and childhood attention deficit hyperactivity disorder (ADHD) in patients with addictions. Psychiatry Res. 2016;246:656-662.

4. Young JT, Carruthers S, Kaye S, et al. Comorbid attention deficit hyperactivity disorder and substance use disorder complexity and chronicity in treatment-seeking adults. Drug Alcohol Rev. 2015;34(6):683-693.

5. van Emmerik-van OK, van de Glind G, Koeter MW, et al. Psychiatric comorbidity in treatment-seeking substance use disorder patients with and without attention deficit hyperactivity disorder: results of the IASP study. Addiction. 2014;109(2):262-272.

6. Levin FR, Evans SM, Vosburg SK, et al. Impact of attention-deficit hyperactivity disorder and other psychopathology on treatment retention among cocaine abusers in a therapeutic community. Addict Behav. 2004;29(9):1875-1882.

7. Cunill R, Castells X, Tobias A, Capella D. Pharmacological treatment of attention deficit hyperactivity disorder with co-morbid drug dependence. J Psychopharmacol. 2015;29(1):15-23.