The effects of anxiety on the process of change and substance use outcomes

Anxiety and substance use disorders rank among the most common and difficult to treat co-occurring psychiatric conditions in the Western world. This dissertation sought to better understand the relationship between these disorders and how they impact one-another. To meet this aim, this dissertation explored data from a study conducted by Velasquez and colleagues (in press), known as Project TIP (Traumatic Injury Prevention). Because Project TIP demographics were similar to demographics found among the military, this dissertation was able to draw parallels between the two populations and generate findings applicable to both the general public and the military. This study addressed two primary questions. First, does anxiety impact substance use outcomes; and second, how does anxiety impact the process of change for substance use? T-tests, general linear model (GLM) profile analyses, GLM repeated measures analyses, and latent growth curve analyses were used to test hypotheses that: 1) increased anxiety would negatively impact substance use outcomes; 2) anxiety and non-anxiety groups would experience substance use change differently; and 3) those with anxiety would differ in their trajectory (degree of change) in accordance with Transtheoretical Model (TTM) constructs over time. Several key findings emerged from this dissertation. The first was that anxiety’s impact on substance use was drug dependent, which indicates future research should compare specific substances or categories of substances, rather than lumping all substances into a single category. Additionally, the two groups experienced change in different ways in accordance with TTM constructs, which were also substance dependent. Primarily, the anxiety group maintained a higher state of readiness to change across the study, but never overcame their perceived cons for change or temptations to return to use. Overall, while both groups’ substance use improved to a similar degree, prior research suggests that because the anxiety group reported an overall higher readiness to change, the anxiety group could have changed at a greater rate, had their self-efficacy concerns been addressed. Therefore, clinicians should avoid the “one size fits all” approach and endeavor to tailor treatment regimens for those with anxiety