Serotonergic involvement in the psychosocial dimension of personality

Neurotransmitter systems have been associated with aspects of personality a nd changes in various dimensions have been shown after antidepressant treat ment. A reduction in harm avoidance and an increase in self-directedness an d cooperativeness, as measured by the Cloninger's Temperament and Character Inventory (TCI), have been reported in psychiatric patients receiving trea tment with serotonergic antidepressants. However, some of these changes hav e been associated with clinical improvement. The present study therefore us ed a randomized, double-blind, placebo-controlled design to examine the rol e of the serotonergic system on these personality factors in the normal pop ulation. Twenty healthy male volunteers were randomly allocated to either p lacebo (n = 9) or citalopram treatment (n = 11) for 2 weeks. Baseline depre ssion and anxiety scores were low and did not differ between groups. The TC I was administered pre- and post-treatment. There were no baseline differen ces on any TCI factor between groups. Citalopram induced a significant incr ease in self-directedness (p < 0.05) but not cooperativeness or harm avoida nce ratings after treatment. Thus, citalopram has effects on personality as pects which appear to be separate from its antidepressant properties.