Importance: Although problem solving has been an important component of successful depression prevention and treatment interventions, evidence to support problem solving's mechanism of action is sparse.
Objective: To understand the mechanism of an efficacious depression prevention intervention, problem-solving education (PSE).
Design, setting, and participants: A multivariate path analysis was embedded within a randomized efficacy trial (February 15, 2011, to May 9, 2016). Participants were mothers with depressed mood, anhedonia, or depression history (but not in current major depressive episode) at 1 of 6 Head Start agencies. Participants were followed up for 12 months with serial assessments of potential intervention mediators and depressive symptoms.
Interventions: Problem-solving education (n = 111) and usual Head Start services (n = 119).
Main outcomes and measures: Primary outcomes were depressive symptom elevations, which were measured bimonthly. Eight plausible intervention mediators were assessed: problem-solving ability; mastery; self-esteem; perceived stress; behavioral activation; and avoidant, problem-focused, and social coping.
Results: Among 230 participants, 152 (66.1%) were Hispanic; mean (SD) age was 31.4 (7.3) years. Based on associations with either PSE participation or depressive symptom outcomes, problem-solving ability, perceived stress, behavioral activation, and problem-focused coping were included in a parsimonious, multivariate path model. In this model, only perceived stress was associated with both PSE participation and depressive symptoms. Participants in the PSE group had adjusted standardized perceived stress change scores that were 11% lower than controls (95% CI, -0.19 to -0.03), and improvement in perceived stress generated an adjusted rate ratio (aRR) of 0.42 (95% CI, 0.33-0.53) for depressive symptom elevations. Participants in the intervention group also had standardized behavioral activation change scores 15% greater than controls (95% CI, 0.01-0.30) and problem-focused coping change scores 17% greater than controls (95% CI, 0.03-0.31); however, changes in these constructs were not associated with a differential rate of depressive symptom elevations. The direct effect of PSE on depressive symptom elevations (aRR, 0.72; 95% CI, 0.52-0.97) was greater than the mediated effect explained by improvement in perceived stress (aRR, 0.91; 95% CI, 0.85-0.98).
Conclusions and relevance: Problem-solving education is efficacious in preventing depressive symptoms and appears to work by decreasing perceived stress; however, the mechanism for much of PSE's impact on depression remains unexplained. These results can be used to simplify the intervention model in preparation for effectiveness testing.
Trial registration: ClinicalTrials.gov Identifier: NCT01298804.