BACKGROUND: Previous studies showed impaired decision-making in suicide attempters, but the cognitive mechanisms in play and subgroup differences among attempters need further research. Understanding these differences is crucial for developing targeted interventions.

METHODS: For the present case-control study, we recruited 49 depressed patients with histories of both mood disorders and suicide attempts, 34 patient controls with no personal history of suicide attempts, and 49 healthy controls. The participants completed clinical assessments and decision-making tasks: the Iowa-Gambling-Task (IGT), a value-based decision-making battery, a mixed gambling task, and a Go/No-Go task. The study was preregistered at ClinicalTrial.gov (NCT05230043).

RESULTS: Both patient groups showed lower IGT performance, and only suicide attempters lower loss aversion than healthy controls. Compared to both patient and healthy controls, suicide attempters exhibited more total and commission errors on the Go/No-Go task. Subgroup analysis revealed that patients who made an impulsive suicide attempt had higher delay discounting and lower loss aversion rates than healthy controls. Meanwhile, attempters who chose violent means performed worse than those with a non-violent means in the first phase of the IGT and had lower loss aversion compared to both control groups. Finally, poorer IGT performance was associated with lower loss aversion and higher suicidal intent.

DISCUSSION: In addition to deficits in response inhibition in depressed suicide attempters, these findings highlight reduced sensitivity to losses, higher delay discounting and impaired value-based learning in impulsive or violent suicidal acts. They, therefore, underscore the heterogeneity within suicide attempters and highlight the need for individualized approaches in future research and clinical interventions.