Cocaine use disorder: anhedonia and emotional flattening in an emotional picture rating task.

OBJECTIVES: Anhedonia, the reduced capacity to experience or pursue pleasure, is common among individuals with cocaine use disorder (CUD). This blunted emotional experience may extend beyond diminished positive affect to include reduced sensitivity to negative emotions. This narrowing of the emotional spectrum, if also present in individuals with CUD, may offer a target for treatment strategies. We hypothesized that individuals with greater anhedonia would rate images more neutrally and that this emotional flattening would extend to physiological responses, including heart rate reactivity and facial muscle activity (corrugator EMG).

METHODS: To test this, 53 participants diagnosed with moderate-to-severe CUD completed the Snaith-Hamilton Pleasure Scale (SHAPS) and the Emotional Picture Rating Task (EPRT). In the EPRT, participants viewed 36 emotional images (positive, neutral, and negative) and rated valence and arousal, while heart rate and corrugator EMG were recorded.

RESULTS: Mixed-effects models revealed a significant interaction between picture type and anhedonia on valence ratings, indicating that higher anhedonia was associated with reduced differentiation in valence. A quadratic pattern emerged for arousal ratings, but anhedonia did not significantly moderate this effect. Physiologically, anhedonia did not influence heart rate deceleration or acceleration, but typical emotional heart rate patterns were not observed. Corrugator activity varied by picture type as expected, but did not differ by anhedonia level.

CONCLUSIONS: These findings suggest that while anhedonia in CUD is associated with subjective emotional flattening, this is not mirrored in physiological measures. These findings highlight the value of interventions that increase emotional sensitivity across the full emotional spectrum (e.g., Acceptance and Commitment Therapy).