Platelet serotonin and [3H]paroxetine binding correlate with recurrence of suicidal behavior

To distinguish state- from trait-dependent associations between serotonergic function and suicidal behavior, platelet serotonergic measures were repeatedly measured, during a 1-year follow-up, in 106 patients who had recently attempted suicide for at least a second time. A major DSM-III-R axis I diagnosis or use of antidepressants were reasons for exclusion. A higher affinity constant (KD) of platelet [3H]paroxetine binding was related to a higher risk of short-term recurrence of a suicide attempt, suggesting a state relationship. Higher levels of platelet serotonin at baseline were a significant predictor of a recurrent suicide attempt within the year of follow-up, suggesting a trait relationship. These associations held equally within the subgroup of 73 patients with a borderline personality disorder. Neither the maximum number of binding sites (Bmax) of [3H]paroxetine nor platelet monoamine oxidase activity correlated with suicidality. The observed association between indicators of platelet serotonin uptake and suicidal behavior suggests a state- and trait-dependency between suicidality and central serotonergic dysfunction.