The role of elevated depressive symptoms on the transtheoretical model variables in substance use disorders
Depression frequently co-occurs with substance use disorders, which are a severe health and financial burden on our society (Office of National Drug Control Policy, 2011; Office of National Drug Control Policy, 2014). This study examined transtheoretical model of change (TTM) constructs in individuals with elevated depressive symptoms and a comorbid substance use disorder, looking to better understand how the depressive symptoms influenced the individuals’ changing substance use behavior. This study was conducted at the Substance Abuse Research Center in the University of Texas Mental Sciences Institute in Houston, Texas in 2006. Participants (N=138) who met the DSM-IV criteria for cocaine use or dependence disorder were recruited. The sample was 72.2% Black, 19.4% White, and 8.3% Latino. Participants were in one of two treatment conditions for cocaine use disorder: 1) a TTM group intervention, modified for cocaine users, or 2) the control condition, an education and advice group. Data on substance use, TTM constructs, symptoms of behavioral health disorders, and other factors were collected at the beginning of the intervention, the end of the intervention, and three months post-intervention. Profile analysis and general linear model (GLM) analysis of variance (ANOVA) were used to examine the hypotheses that cocaine users with elevated depressive symptoms would endorse the TTM constructs differently than the nondepressed participants, especially the processes of change constructs, but would reduce their cocaine use the same amount as the nondepressed users. This study found that participants with elevated depressive symptoms were as successful as nondepressed participants in reducing their cocaine use after treatment. However, participants with elevated depressive symptoms engaged with the TTM variables differently compared to nondepressed participants, especially the processes of change and temptation variables. The behavioral processes of change were significantly lower before treatment and the experiential processes of change were significantly higher after treatment compared to nondepressed participants. Temptation was higher in participants with elevated depressive symptoms compared to nondepressed participants and lower temptation in participants with elevated depressive symptoms was linked to more successful reduction in cocaine use. These findings indicate that temptation and the processes of change are important variables to target in treatment of substance use disorders in adults with elevated depressive symptoms.