Mapping valence-specific affective flexibility deficits in depression: Neurobehavioral dissociations revealed by...

Affective flexibility deficits in Major Depressive Disorder (MDD) are hypothesized to reflect valence-specific impairments in shifting between emotional and non-emotional processing. However, the underlying neurophysiological mechanisms remain poorly understood.

Twenty-nine individuals with MDD and twenty-nine healthy controls (HCs) completed a modified Affective Switching Task (AST) requiring rapid alternation between judging emotional valence (positive/negative) and counting human figures, while undergoing 64-channel EEG recording. Behavioral switch costs and event-related potentials (ERPs), particularly the Late Positive Potential (LPP), were analyzed across positive and negative contexts using mixed-design ANOVAs and correlation analyses.

MDD participants showed significantly elevated positive engagement switch costs (PE-SC) compared to HCs (F_(1,56) = 5.072, p = 0.028, η²ₚ = 0.083), which positively correlated with depression severity (r = 0.48, p = 0.009). At the neural level, MDD participants exhibited significantly reduced LPP modulation during negative engagement (NE-LPPD; F_(1,56) = 5.490, p = 0.023, η²ₚ = 0.089), indicating impaired emotional resource allocation. Moreover, enhanced negative disengagement predicted greater LPP responses to positive engagement, suggesting a compensatory resource reallocation mechanism. Notably, behavioral and neural indices were dissociated in positive trials, suggesting a potential imbalance between compensatory and depleted neural processes.

These findings provide novel ERP-based evidence of valence-specific affective flexibility deficits in MDD, characterized by behavioral difficulty engaging with positive stimuli and attenuated neural responsiveness during negative processing. This valence asymmetry may underlie emotional rigidity in depression and highlight neurocognitive targets for intervention.