Neural Responsiveness to Reward as an Index of Depressive Symptom Change Following Cognitive-Behavioral Therapy and SSRI Treatment

Objective: Reward positivity (RewP), a neurophysiologic index of reward responsivity, is consistently reduced in participants with depression and, to a lesser extent, anxiety. It remains unknown, however, whether RewP can be altered as psychiatric symptoms change with treatment. The current study addressed this question by examining differences in RewP within patients before and after 12 weeks of treatment with a selective serotonin reuptake inhibitor (SSRI) or cognitive-behavioral therapy (CBT). We also examined the utility of RewP as a predictor of symptom change during CBT and SSRI treatment. Methods: Participants were recruited between 2014 and 2017 and included adults with a primary DSM-5 anxiety or depressive disorder (n=63) and healthy controls (n=25). At baseline and 12 weeks, participants completed a monetary award task while electroencephalogram (EEG) was recorded. Between EEG sessions, patients completed CBT or SSRI treatment. Results: At baseline, higher levels of depressive symptoms were associated with a more attenuated RewP. We found no significant differences between patients and healthy controls in the degree of RewP change across the 12 weeks; however, among patients, the extent of increase in RewP robustly correlated with the extent of decline in depressive (t=-2.21, P=.03) and anxiety (t=-2.57, P=.02) symptoms following CBT and SSRI treatment. Additionally, a more attenuated RewP at baseline predicted a greater reduction in depressive symptoms following treatment with SSRIs (t=-2.04, P<.05), but not after CBT. Conclusions: These findings highlight neural responsiveness to reward as both a mechanism and a predictor of depressive symptom change that may be used serve as an objective index of symptom improvement.