Prediction of drop-out and outcome in integrated cognitive behavioral therapy for ADHD and SUD: Results from a randomized clinical trial

Abstract Background Patients with substance use disorder (SUD) or Attention Deficit Hyperactivity Disorder (ADHD) have a high risk of drop out from treatment. Few studies have investigated predictors of therapy drop out and outcome in SUD patients with comorbid ADHD. Recently, integrated cognitive behavioral therapy (CBT/Integrated) was shown to be more effective than standard CBT (CBT/SUD) in the treatment of SUD+ADHD. Objective To investigate the association of demographic, clinical and neurocognitive variables with drop-out and treatment outcome, and to examine which of these variables are suitable for patient-treatment matching. Methods We performed an RCT in which 119 patients were allocated to CBT/Integrated (n=60) or CBT/SUD (n=59). In addition, 55 patients had dropped out before randomization. Demographic variables, clinical characteristics and measures of cognitive functioning (Stroop, Tower of London (ToL) and Balloon Analogue Risk Task (BART)) were included as predictors. Outcome measures were: early treatment drop-out, ADHD symptom severity, and substance use severity at end of treatment and follow up. Results Primary substance of abuse (drugs as opposed to alcohol only) and lower accuracy scores on the ToL were significant predictors of early treatment drop-out. Having more depression and anxiety symptoms and using ADHD medication at baseline significantly predicted more ADHD symptoms at end of treatment, and higher accuracy scores on the ToL significantly predicted higher substance use at end of treatment. No significant predictor-by-treatment interactions were found. Conclusion The results add to the existing realization that also relatively mild cognitive deficits are a risk factor for treatment drop-out in these patients.