Better to give than to take? Interactive social decision-making in severe major depressive disorder

Although recent studies focusing on major depressive disorder (MDD) suggest altered social decision-making, studies using the Ultimatum Game (UG) in patients with severe, clinical MDD do not exist. Moreover, all aforementioned studies so far focused on responder behavior and thus fairness considerations; to this date, no one investigated social interactive behavior which involves proposer behavior possibly requiring second-order mentalizing as well.

Thirty-nine MDD patients and 22 healthy controls played a modified UG, both in the roles of responder and proposer against the same partner.

MDD patients accepted both fair and unfair offers as many times as the healthy controls in their role as responder. Importantly, however, in the role of proposer MDD patients offered significantly more than the control group did.

Most patients were treated with psychotropic medication.

Responder behavior demonstrates that MDD patients are capable of making social decisions on fairness considerations in the same way as healthy controls do. The observed proposer behavior, however, could indicate that MDD patients are more focused on avoiding rejection. These findings provide unique evidence that social decision-making--as studied in a realistic context--is disturbed in MDD.