SELECTIVE ALTERATION OF PERSONALITY AND SOCIAL-BEHAVIOR BY SEROTONERGIC INTERVENTION

Objective: The authors sought to test the causal hypothesis that serot onergic Junction modulates aspects of the normal spectrum oi individua l differences in affective experience and social behavior in humans. M ethod: A selective serotonin reuptake inhibitor (SSRI), paroxetine, 20 mg/day (N=26), or placebo (N=25) was administered to normal volunteer s in a double-blind manner for 4 weeks, and personality variables and social behavior were assessed at baseline and at weeks 1 and 4 of trea tment. Results: Relative to placebo, SSRI administration I educed foca l indices of hostility through a more general decrease in negative aff ect, yet did not alter indices of positive affect. In addition, SSRI a dministration increased a behavioral index of social affiliation. Chan ges in both negative affect and affiliative behavior were significantl y related to volunteers' plasma SSRI levels at the end of the experime nt. Conclusions: Central serotonergic function may modulate a dimensio n of normal personality characterized by reduced negative affective ex perience and increased affiliative behavior. SSRI administration has s ignificant and detectable effects on these measures even in the absenc e oi baseline clinical depression or other psychopathology.