The roles of borderline personality disorder symptoms and dispositional capability for suicide in suicidal ideation and suicide attempts: Examination of the COMT Val158Met polymorphism

•Individuals with borderline personality disorder (BPD) are at high risk for suicide.•Current suicide models suggest dispositional capability may explain this risk.•We examined COMT Val158Met polymorphism in the relation between BPD and suicide.•BPD-suicidal ideation relation was not influenced by the Val158Met polymorphism.•Lifetime suicide attempt more likely in Val/Val carriers with more BPD symptoms. There is a need to identify the subset of individuals with borderline personality disorder (BPD) symptoms at greatest risk for transitioning from suicidal ideation to a suicide attempt. Contemporary models of suicide risk propose that the capability for suicide is necessary for moving from suicidal ideation to a suicide attempt. Few studies have examined dispositional capability factors for suicide, especially among individuals with BPD symptoms. One candidate may be the catechol-o-methyltransferase (COMT) Val158Met polymorphism given its influence on pain sensitivity and fear. This study examined the interactive relation of BPD symptoms and the COMT Val158Met polymorphism to suicidal ideation and suicide attempts. Fifty-nine treatment-seeking patients were recruited. Participants were administered a series of clinical interviews to evaluate BPD symptoms and suicidal thoughts and behaviors. Saliva samples were collected for genotyping. The relation between BPD symptoms and suicidal ideation was not influenced by the Val158Met polymorphism. However, among Val/Val carriers, the probability of a lifetime suicide attempt increased as BPD symptom severity increased. Findings provide preliminary support for the Val/Val variant as a dispositional factor that may increase risk for suicide attempts in BPD; however, results must be interpreted with caution until replication of findings occurs in larger samples.