Reward/Punishment Reversal Learning in Older Suicide Attempters

The authors hypothesized impairment in reward/punishment-based learning is associated with attempted suicide in late-life depression. A probabilistic reversal learning task was used with 65 individuals age 60 & older: suicide attempters, suicide ideators, nonsuicidal depressed elderly, & nondepressed comparison subjects. A reinforcement learning computational model was used to decompose reward/punishment processing over time. Attempters but not ideators showed impaired probabilistic reversal learning compared to both nonsuicidal depressed elderly & nondepressed comparison subjects. Model-based analyses revealed suicide attempters discounted previous history to a higher degree relative to comparison subjects. Groups did not differ in their performance on the Stockings of Cambridge test. (55 refs.) JA