Researchers at the Langley Porter Institute in San Francisco report that the antidepressant paroxetine (Paxil), a selective serotonin reuptake inhibitor (SSRI), improves cooperation and reduces hostility in healthy volunteers.
The 51 subjects were divided into two groups and given either paroxetine or a placebo for four weeks. They were interviewed three times in the course of the study: at the beginning, after one week, and at the end. After each interview they were asked to collaborate with a partner in solving a problem that resembled a jigsaw puzzle. The partnerships, which were new each time, always consisted of one person taking the drug and one taking the placebo. The subjects were videotaped while they worked on the puzzle, and raters judged their emotional expressions and their ability to cooperate (make suggestions rather than issue commands, avoid unilateral attempts at solutions). A week after starting to take paroxetine, the subjects became more cooperative and showed less anger and anxiety while solving the puzzle. They also scored lower on a questionnaire measuring hostility. Happiness, excitement, and other pleasant feelings were not affected, and there was no change between week one and week four.
These changes in behavior and mood came sooner than the usual antidepressant response, which takes several weeks or more, and were strongly correlated with the blood level of the drug, which is not generally a good measure of its antidepressant effect. The authors conclude that SSRIs can have favorable effects on mood and behavior even in people without psychiatric symptoms, chiefly by reducing unpleasant feelings rather than heightening pleasant ones. They add that the study confirms earlier findings that hostility can be reduced by raising the level of serotonin in the brain.
Brian Knutson, Owen M. Wolkowitz, Steve W. Cole, et al. Selective alteration of personality and social behavior by serotonergic intervention. American Journal of Psychiatry 155: 373-379 (March 1998).
