Personality traits in bipolar disorder type I: a sib-pair analysis

The aim of this study was to compare temperament and character traits among patients with bipolar disorder (BD), their siblings, and healthy controls (HCs) in order to examine whether personality traits are related to the genetic vulnerability to develop BD.

Using the Temperament and Character Inventory, we assessed 204 subjects: 67 euthymic outpatients with bipolar disorder type I, 67 siblings without BD, and 70 HCs.

Scores on harm avoidance, novelty seeking, and self-transcendence were significantly higher among patients with BD than among HCs, whereas those on self-directedness and cooperativeness were significantly lower. Siblings showed higher scores on harm avoidance and lower scores on self-directedness than did HCs. As some of the siblings presented at least one lifetime psychiatric disorder other than BD (n = 35), we examined the subset of siblings who had no lifetime psychiatric disorder (n = 32). This group showed statistically higher harm avoidance scores than HCs.

Our results suggest that the harm avoidance temperament trait and, to a lesser extent, the self-directedness character trait may represent vulnerability factors for BD.