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.