Early Change in Neural Circuit Function Engaged by Negative Emotion Mediates Later Depression and Problem-Solving Outcomes Following Behavioural Intervention

Background: There is a need to understand the neural mechanisms targeted by behavioural therapy for depression and how these mechanisms relate to clinical outcomes. We used functional neuroimaging to assess the neural mechanisms that are modified by behavioural therapy and mediate subsequent clinical outcomes in depression. Methods: Participants with depression, co-occurring with obesity, from a parent RAINBOW trial, were randomised to an integrated collaborative care intervention (I-CARE) (n=59) or usual care (n=49). Functional neuroimaging was undertaken at baseline and at 2 months, coinciding with initial 2-months of I-CARE that implemented a 7-step problem-solving therapy process and behavioural activation (for brevity, “PST”). Neural targets were the amygdala, insula, and anterior cingulate cortex (ACC) regions of the negative affect circuit engaged by established tasks presenting threat-related and sad stimuli. Regression models evaluated if early change in neural function mediated the effect of PST on depression severity and problem-solving outcomes at 6- and 12-months post-randomization. Findings: Compared with usual care, PST led to a reduction at 2 months in amygdala activation (Right: b=-0.83, 95% CI -1.55 to -0.11; Left: b=-0.86, -1.63 to -0.10) and amygdala-ACC connectivity (b=0.78, 0.05 to 1.52) engaged by threat stimuli. This PST-dependent reduction in amygdala activation mediated improvement of depression at 6 months relative to usual care. PST also tempered the relationship between insula activation and improved problem solving at 6 and 12 months. Interpretation: PST modifies neural targets within the negative affect circuit to improve symptoms and problem-solving relevant to the clinical and functional recovery of depression. Funding Statement: US National Institutes of Health/National Heart Lung and Blood Institute R01 HL119453 and UH2/UH3 HL132368. Declaration of Interests: LMW is on the Scientific Advisory Board for One Mind Psyberguide and the External Advisory Board for the Laureate Institute for Brain Research. JM is a paid scientific consultant for Health Mentor, Inc. (San Jose, CA). OA is the co-founder of Keywise AI and the servers on the advisory boards of Blueprint Health and Embodied Labs. All other authors do not have anything to declare. Ethics Approval Statement: The Institutional Review Boards for the Stanford University and the University of Illinois at Chicago approved the study.