In the ACT condition, shame at posttreatment was unrelated to weeks with substance use at follow-up, Spearman’s r(31) = .09, p = .64, while shame at follow-up was related to use at follow-up, r(34)=.47, p = .005. In the TAU arm, a correlation approached significance where lower levels of shame at posttreatment predicted more weeks of substance use, r(31) = −.301, p = .10, at follow-up, but follow-up shame was unrelated to substance use, r(36) = .21, p = .21. When observing pre- to postassessment changes in shame, greater decreases in shame from pre- to post-treatment in the TAU arm predicted a significantly higher number of weeks with substance use during follow-up, r(31) = −.41, p = .02, a relationship that was similar in the ACT condition, r(31) = −.36, p = .04. Together, these results suggest that there was something artificial or unsustainable about the shame levels produced in the TAU condition, a process that was ameliorated somewhat in the brief ACT intervention, where few people showed a sharp decrease in shame scores. This possibility was further explored in the context of a mediation analysis.
