Impaired flexible decision-making in Major Depressive Disorder.

BACKGROUND: Depression is associated with dysfunctional affective states, neuropsychological impairment and altered sensitivity to reward and punishment. These impairments can influence complex decision-making in changing environments.
METHODS: The contingency shifting variant Iowa Gambling Task (IGT) was used to assess flexible decision-making performance in a group of medicated unipolar Major Depressive Disorder (MDD) patients (n=19) and a group of healthy control volunteers (n=20). The task comprised the standard IGT followed by a contingency-shift phase where decks progressively changed reward and punishment schedule.
RESULTS: Patients with MDD showed impaired performance compared to controls during both the standard and the contingency-shift phases of the IGT. Analysis of the contingency-shift phase demonstrated that individuals with depression had difficulties perceiving when a previously bad contingency became good. LIMITATIONS: The present findings have several limitations including small sample size, the possible confounding role of medication and absence of other neuropsychological tests (i.e., executive function).
CONCLUSION: Depressed patients show impaired decision-making behaviour in static and dynamic environments. Altered sensitivity to reward and punishment is proposed as the mechanism responsible for the lack of advantageous choices and poor adjustment to a changing environment.