Neuropsychological Functioning and Outcomes of Treatment for Co-occurring Depression and Substance Use Disorders

Abstract

Background: We previously published findings from our clinical trial comparing treatment outcomes for substance-dependent veterans with co-occurring depression who received Integrated Cognitive Behavioral Therapy (ICBT) or Twelve-Step Facilitation (TSF) Therapy. Objectives: This study is a secondary analysis that examined whether neuropsychological functioning at baseline moderated substance use and depression outcomes in ICBT relative to TSF. Methods: This study was a randomized clinical trial in which 164 veterans with major depressive disorder and comorbid alcohol, cannabinol, and/or stimulant dependence were randomly assigned to either ICBT or TSF group therapy. A comprehensive neuropsychological test battery was administered at baseline. Results: Contrary to our hypothesis, participants with poor neuropsychological functioning had better substance use outcome in ICBT than in TSF, whereas participants with good neuropsychological functioning had comparable substance use outcomes in TSF and ICBT by 18-month follow-up. Depression outcomes, in contrast, were not moderated by neuropsychological functioning by 18-month follow-up. Conclusions and Scientific Significance: The substance use outcomes may suggest that substance-dependent depressed adults with poorer neuropsychological functioning should be offered ICBT over TSF. These individuals may be less able to develop and use novel coping skills for managing substance use and depressive symptoms on their own without formal structured training in cognitive and behavioral skills provided in ICBT.

• depression
• substance use disorders
• cognitive behavioral therapy
• neuropsychological impairment

ACKNOWLEDGMENTS

Funding for this study was provided by a VA Medical Research Merit Review Grant awarded to Dr. Sandra A. Brown and a VA Medical Research Merit Review Grant to Dr. Susan R. Tate.

Declaration of Interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Notes

1. We explored whether specific cognitive domains moderated outcomes (i.e., used the same mixed effects model to test whether the three-way interaction between treatment group, baseline NP domain T-score, and time-squared quadratic term was significant, as was found for the global NP T-score). We found that all cognitive domains significantly moderated at least one of the two outcomes. Significant moderation of depression outcome (HAM-D) was found for verbal IQ, coeff. = −.0111, t = −2.83, p = .006, visuospatial construction, coeff. = −.0095, t = −2.56, p = .012, and verbal learning, coeff. = −.0061, t = −1.96, p = .051 (marginal), but not for executive functions, coeff. = .0025, t = .50, p = .619, or attention, coeff. = −.0026, t = −.48, p = .634. Significant moderation of substance use outcome (PDA) was found for verbal IQ, coeff. = −.0004, t = −2.34, p = .021, executive functions, coeff. = −.0003, t = −2.60, p = .010, attention, coeff. = −.0005, t = −2.54, p = .013, and visuospatial construction, coeff. = −.0002, t = −1.66, p = .098 (marginal), but not verbal learning, coeff. = .00004, t = .37, p = .715.