Background: Attention-deficit/hyperactivity disorder (ADHD) and substance use disorder are often comorbid in adults. The effects of ADHD treatment on comorbid alcohol use disorder have not been extensively studied.
Objective: To assess correlates of ADHD and alcohol use outcomes in ADHD with comorbid alcohol use disorders, via a post-hoc exploratory subgroup analysis of a previously conducted, randomized, double-blind, placebo-controlled study of recently abstinent adults.
Methods: Adults who had ADHD and alcohol use disorders and were abstinent for 4-30 days were randomized to daily atomoxetine 25-100 mg (mean final dose = 89.9 mg) or placebo for 12 weeks. Changes in ADHD symptoms from baseline to endpoint were assessed using the ADHD Investigator Symptom Rating Scale (AISRS) total score, alcohol use by the timeline followback method, and alcohol cravings by the Obsessive Compulsive Drinking Scale.
Results: Of 147 subjects receiving atomoxetine (n = 72) or placebo (n = 75) in the primary study, 80 (54%) completed 12 weeks (n = 32 atomoxetine; n = 48 placebo). Improvements in ADHD symptoms on the AISRS correlated significantly with decreases in alcohol cravings (Pearson's r = 0.28; 95% confidence interval [CI] = 0.11-0.43; p = 0.002), and the correlation was most notable with atomoxetine (r = 0.29; CI [0.04 - 0.51]; p = 0.023) rather than with placebo (r = 0.24; CI [0.00-0.46]; p = 0.055). On-treatment drinking levels correlated with AISRS scores (r = 0.12; CI [0.05 -0.19]; p = 0.001). Relapse to alcohol abuse significantly correlated with worse ADHD symptoms on 15 of 18 items of the AISRS in the placebo group (p < 0.05 for each).
Conclusions: No baseline predictor (other than degree of sobriety) of alcohol use or ADHD outcomes emerged. ADHD symptom improvements correlated significantly with reductions in alcohol cravings, and relapse to alcohol abuse correlated significantly with worsening of most ADHD symptoms in the placebo group, but not in the atomoxetine group. This post-hoc subgroup analysis is of a hypothesis-generating nature, and the generalizability of the findings may be limited by exclusion of adults with common ADHD comorbidities from the base study. Further, prospective clinical trials in larger and more heterogeneous patient populations are warranted to confirm or reject these preliminary associations. TRIAL REGISTRATION (BASE STUDY): ClinicalTrials.gov identifier: NCT00190957.