Exploring risky decision-making dynamics during antidepressant treatment in major depressive disorder: a computational modeling approach.

Background: Patients with major depressive disorder (MDD) show greater loss sensitivity and higher delayed discounting rates during decision making, but findings regarding their risk preferences are inconsistent. Computational behavioral modeling provides a promising tool for the investigation of these latent factors underlying the decision-making behaviors.

Objectives: Conduct both cross-sectional and longitudinal analyses to identify patterns and changes in risky decision-making over time, examine correlations between traditional CGT performance indicators and cognitive modeling parameters to better understand the underlying mechanisms of decision-making, and separately explore participants' reward and loss sensitivities.

Methods: At baseline, 52 patients with MDD and 66 healthy controls (HCs) underwent psychometric assessment and performed the Cambridge gambling task (CGT) characterizing risky decision-making behavior. After 8 weeks of treatment with the selective serotonin reuptake inhibitor, the patient group underwent assessment and performed the CGT again. Applying a cumulative model to the trial-by-trial behavioral data of the CGT, we also compared the latent factors between groups, including probability distortion, color bias, utility/loss sensitivity, delayed reward discounting and choice consistency.

Results: Patients with MDD had more depressive symptoms and anhedonia than did HCs. MDD group exhibited both greater delayed reward discounting and lower choice consistency than HCs. After the treatment, MDD group had both decreased loss sensitivity and color choice bias. Controlling for depressive symptoms, a deficit in consummatory pleasure with motivational drive was associated with greater delayed reward discounting at baseline in MDD group.

Conclusions: Our findings suggest that patients with MDD have deficits in reward function (higher delayed reward discounting and lower risk adjustment) at baseline. With antidepressant treatment, loss sensitivity decreased while impairment in reward function persists, and these patients tend to make more risky choices after treatment.

Trial registration: The registration number is ChiCTR2000031931 and date of registration is April 15th 2020.