The Neurophysiological Substrate of the Decision-Making Process in Depressed Patients

Abstract

Background: The neural circuits involved in the decision-making process and social emotion participate in the same circuits seen in major depressive disorder. This study aimed to investigate in depressed patients, the decision making process in risk/reward situations using neurophysiological methods for a better assessment of functional aspects related to decision making deficit that are seen in major depression. Methods: Forty patients were studied, 20 with depression and 20 without. After applied the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I) and Hamilton Depression scale (HAM-D), the Iowa Gambling Task (IGT) was applied to analyze the risk/ reward decision-making behavior. The Skin Conductance Response (SCR) was recorded to analyze the emotional anticipatory learning effect during the IGT. Besides, an EEG was recorded to measure the Frontal Alpha Asymmetry Index (FAAI). Results: Depressed patients presented a lower Net score and a deficit in anticipatory learning effect in the IGT. Furthermore, the FAAI revealed more frontal right activation as have described in previous studies. Conclusion: Patients with major depression have a dysfunction in the circuits that modulate cognitive, emotional and social behavior, and also, impairment in cognitive fluidity for evaluating strategies for risk-reward. The EEG helps to confirm that asymmetry in frontal areas and oscillation of alpha frequencies participate in the regulation of emotion in depressed patients.