We recently reported that decision-making impairment may be a neuropsychological trait of vulnerability to suicidal behavior (SB), that may reflect a serotonergic dysfunction in the orbitofrontal cortex.

We used the Iowa Gambling Task to assess decision-making in euthymic suicide attempters and controls with a history of affective disorders but no history of SB, and healthy controls. We explored 1) the link between decision-making deficit and relevant clinical variables; 2) the role of serotonin related polymorphisms relevant to SB in decision-making processes; 3) the link between life events on the last 12 months and decision-making.

1) In a sample of more than 300 psychiatric patients, we found that a decision making impairment was associated with the vulnerability to SB independently of the psychiatric diagnoses. Decision making was negatively correlated with emotional dysregulation, but not with impulsivity. No association was found between decision-making performance for suicidal lethality, intent, ideation, number of suicide attempts, age at first suicide attempt. 2) Suicide attempters carrying the 5HTTLPR-ss or the TPH1-AA genotypes, associated with SB, expressed worse learning abilities during the decision making task. 3) Adult life events and decision-making were correlated in suicide attempters.

We confirm that impaired decision making, possibly due to emotional dysfunction, may be a neuropsychological risk factor for SB independently of psychiatric disorders. In suicide attempters, the influence of genetic factors may partly be achieved through their modulation of the learning processes of decision-making, that may constitute a candidate endophenotype in SB.