Date of Award

Fall 2016

Document Type


Degree Name

Doctor of Philosophy (PhD)


Psychology and Behavioral Sciences

First Advisor

Tony R. Young


Substance use disorders are a widespread issue in society today with approximately 20 million people in the U.S. alone experiencing drug-related problems (Substance Abuse and Mental Health Services Administration, 2012). However, treatment is often ineffectual with approximately 50% of addicted individuals returning to substance use. One factor found to impact individuals' treatment response is their neuropsychological functioning. Drug-abusers frequently exhibit severe executive functioning impairments across a number of domains, and there is evidence that these deficits may be time and substance-dependent. Executive functions are mental processes critical in motivation, planning, and goal-directed behaviors. With extended abstinence, research suggests cognitive improvements will occur for many addicts.

The goal of the present study was to evaluate specific impairments in cognitive abilities and executive functions associated with substance abuse for individuals entering residential treatment and to assess the relationship between self-report executive functioning problems and functioning observed on neuropsychological tests. It was hypothesized that participants would exhibit significant impairments in the areas of working memory, set-shifting, inhibition, planning, verbal fluency, and sustained attention. Further, it was hypothesized that improvements in executive functioning would be observed after approximately 45 days of treatment. Moreover, it was hypothesized that executive functioning measures, both self-report and performance-based, would predict substance-related problems, years of abuse, and problematic personality traits. Finally, better neurocognitive functioning at intake was hypothesized to be related to treatment retention.

This study examined adult participants receiving treatment within a private residential addiction center. Findings generally did not provide support for hypotheses. Results found participants reported significant levels of executive functioning problems but exhibited significantly poorer performance on only one neuropsychological measure (Comprehensive Trail-Making Task) compared to established norms which indicated deficits in set-shifting ability. Further, significant improvements at follow-up testing were observed in only three executive functioning tasks, although fewer executive functioning problems were reported by participants across multiple domains. It may be that more extensive cognitive improvements were not observed given the generally average performance of the sample across the neuropsychological battery administered. Further, the only executive functioning measure found to be a significant predictor of substance-related problems and problematic personality traits was the self-report Barkley Deficits in Executive Functioning Scales. Finally, scores on initial executive functioning measures were not found to be predictive of treatment retention. One possible explanation for these results may be the characteristics of the sample studied as the participants were generally well-educated with likely higher levels of general cognitive functioning compared to similar research.