Altered neural correlates of optimal decision-making in individuals with depressive status

Making optimal decisions by computing risk and benefit is necessary for humans. However, whether individuals with depressive status could utilize the optimal strategy to guide decision and its neural correlates remain unclear. The current study explored these issues by combining a decision task and high temporal-resolution electroencephalogram (EEG). The decision task involved an eight-box trial in which participants successively decided whether to open a box containing a potential reward or punishment, deciding to stop guaranteed they would retain the rewards already accumulated. Theoretically, the optimal strategy in the task was to stop at the fourth box, which had the largest expected value. We found that individuals with depressive status stopped fewer trials at the fourth box, relative to healthy controls, indicating their impaired optimal strategy during decision-making. Moreover, compared to healthy controls, individuals with depressive status showed weaker P2 amplitude and weaker beta-band oscillation at the frontocentral scalp when deciding whether to open the fourth box. Additionally, for healthy controls but not for individuals with depressive status, the P2 amplitude fully mediated the relationship between participants' degree of expected benefit (as reflected by the recreational risk-taking scale) and the frequency of trials stopped at the fourth box. Overall, this study revealed that the P2 amplitude and beta-band oscillation might explain the altered optimal decision-making in individuals with depressive status.