Testing Mechanisms of Change for Text Message–Delivered Cognitive Behavioral Therapy: Randomized Clinical Trial for Young Adult Depression (Preprint)

Abstract

BACKGROUND Current psychiatric epidemiological evidence estimates 17% of young adults (ages 18-25) experienced a Major Depressive Episode (MDE) in 2020, relative to 8.4% of all adults 26 and older. Young adults with past year MDE are the least likely to receive any treatment for depression compared to other age groups OBJECTIVE In an effort to address this need, we conducted a follow-up randomized clinical trial to our initial 4-week text-delivered cognitive behavioral therapy for young adult depression (CBT-txt). We sought to specify the appropriate treatment dosage and identify mechanisms of change for CBT-txt. METHODS Based on participant feedback, outcome data, and the empirical literature, we increased the treatment dosage from 4 to 8 weeks and tested 3 mechanisms of change with 103 U.S. young adults. Participants were from 33 states recruited from Facebook and Instagram, presenting with at least moderate depressive symptomatology. Assessments occurred at baseline prior to randomization and at 1, 2, and 3 months post-enrollment. The primary outcome, severity of depressive symptoms, was assessed using the Beck Depression Inventory II. Behavioral activation, perseverative thinking, and cognitive distortions were measured as mechanisms of change. RESULTS At each of the three follow-ups, participants in the CBT-txt group showed significantly larger decreases in depressive symptoms than those in the control group and produced a medium/large effect size (Cohen’s d = .76). CBT-txt reduced BDI-II scores by 18 points and 53% of the treatment group moved from ‘moderate or severe depressive symptoms’ to ‘none to minimal depressive symptoms.’ Mediation analysis showed that CBT-txt appeared to lead to greater increases in behavioral activation and greater decreases in cognitive distortions and perseverative thinking across the three-month follow-up period, which were then associated with larger baseline-to-three-month decreases in depression. The size of indirect effects was substantial: 57%, 41%, and 50% of the CBT-txt effects on change in depression were mediated by change in behavioral activation, cognitive distortions, and perseverative thinking, respectively. CONCLUSIONS These results provide further evidence for the efficacy of CBT-txt to reduce young adult depressive symptoms through hypothesized mechanisms. To our knowledge, CBT-txt is unique in its text-delivered modality and in its strong clinical evidence supporting efficacy and in identifying mechanisms of change. CLINICALTRIAL ClinicalTrials.gov Identifier: NCT05551702