Assessing the Mediating Impact of Solution-Focused Constructs on Depression, Anxiety, and Well-Being: A Longitudinal Mediation Analysis of a Randomized Control Trial

Background and Purpose: Depression symptoms are pervasive, negatively affect health, increase mortality, and decrease well-being. In addition, depressive disorders are one of the most common co-occurring diagnoses for those with chronic illnesses. However, medical teams rarely assess and address depressive symptoms and other mental health conditions (<50% of the time). Integrated care (IC) models have emerged to address co-occurring depression and chronic illness simultaneously. However, there are few trials adapting solution-oriented approaches within the primary care behavioral health (PCBH) model. Further, even fewer studies analyze change mechanisms detailing how behavioral interventions link to healthcare outcomes. Last, the majority of studies examine depressive symptoms as a unidimensional construct without assessing variability in different symptom profiles of depression. The current study addresses these gaps.

Methods: We conducted a secondary analysis of a single‑site randomized controlled trial (led by the first author) designed to evaluate an IC intervention within primary care. We enrolled 69 adults who screened positive for depression (PHQ‑9 ≥ 10) and had one or more chronic medical conditions (e.g., diabetes, hypertension)—a population at high risk for poor mental and physical health outcomes. Participants were randomized to treatment as usual (TAU)—standard primary care services without any integrated behavioral health or solution‑focused intervention—or to a solution‑focused intervention adapted for the PCBH model.

Primary outcomes were chosen to capture both symptom reduction and broader well‑being: depression severity (PHQ‑9), anxiety severity (GAD‑7), and subjective flourishing (Flourishing Index). To probe how the intervention worked, we measured key solution‑focused constructs—hope, social connectedness, self‑perceived strengths, and problem‑solving confidence—using a solution‑focused core construct scale created by the authors. These constructs map directly onto the intervention’s theoretical framework, which posits that enhancing clients’ strengths and resources drives mental health improvements. We employed a two‑wave longitudinal structural equation mediation model (baseline and post‑intervention) to test whether changes in these constructs statistically mediated improvements in depression, anxiety, and flourishing.

Results: Compared with TAU, the intervention group demonstrated significantly greater reductions in depression (β = –0.83, p<0.01), including both cognitive (β = –0.77, p<0.01) and somatic components (β = –0.78, p<0.01). In addition, significant reductions in anxiety (β = –0.72, p<0.01) and improvements in flourishing (β = 0.62, p<0.01) were observed. Mediation analyses revealed that higher baseline solution-focused core constructs were associated with lower post-treatment depressive symptoms (overall: β = –0.13, p<0.05; cognitive: β = –0.15, p<0.05), lower anxiety (β = –0.15, p<0.05), and higher flourishing (β = 0.21, p<0.05), thereby attenuating the direct intervention effects.

Conclusions and Implications: Within a PCBH model, the brief solution-focused intervention significantly enhanced core constructs that mediated reductions in depression and anxiety while improving overall well-being. Social workers frequently work within PCBH models delivering brief interventions for individuals with depression and chronic illness. These findings highlight the importance of social work researchers and clinicians targeting solution-oriented constructs (e.g. hope, connection to important people, and self-identified strength) to improve health outcomes and well-being.