Altered Inhibitory Control Across Subclinical Depression and Major Depressive Disorder: Evidence From Stroop Tasks and Diffusion Modeling

Inhibitory control deficits are central to cognitive dysfunction in major depressive disorder (MDD), yet how such deficits vary across subclinical depression and MDD remains unclear. Childhood trauma may further contribute to variability in inhibitory control. This study examined behavioral and computational markers of inhibitory control across nonemotional and emotional contexts in healthy, subclinical depression, and MDD groups and explored associations with childhood trauma. Thirty individuals with subclinical depression, 33 patients with MDD, and 36 healthy controls (HCs) completed three Stroop tasks (color-word, emotion, and face-word), during which reaction times (RTs) were recorded. Latent cognitive parameters were estimated using the drift diffusion model (DDM) and diffusion model for conflict tasks (DMCs). Associations between these indicators and childhood trauma were examined. Patients with MDD showed significantly longer RTs than subclinical individuals in emotion and face-word Stroop tasks. Computational modeling revealed prolonged nondecision time in MDD, relative to subclinical depression (color-word Stroop task) and HCs (emotion Stroop task). In the subclinical group, greater childhood trauma was associated with faster RTs in incongruent face-word trials and shorter nondecision time in the color-word Stroop task. Our findings support a possible inverted U-shaped pattern of inhibitory control across depressive severity, with enhanced performance in subclinical depression but poorer performance in MDD. Enhanced inhibitory control in subclinical depression may reflect compensatory adaptation linked to early adversity. These findings provide novel insights into stage-related differences of inhibitory control in depression.