The degree to which a person is easy-going or irritable--a personality trait thought to be one of the stable touchstones of identity--can be shifted more toward the easy-going side by a drug used to treat depression, University of California San Francisco researchers report.
The evidence that drugs can act on the brain to change once-stable measures of personality is published in the March issue of the American Journal of Psychiatry by a UCSF research team led by Victor Reus, MD, and Owen Wolkowitz, MD, professors of psychiatry at UCSF, and by postdoctoral fellow Brian Knutson, PhD.
Twenty-three mentally healthy men and women, average age 27, who took the anti-depressant paroxetine for four weeks as part of the study scored lower on survey questionnaires used to measure hostility and exhibited more engaging and cooperative behavior in puzzle-solving tasks with a partner than they did at the beginning of the study.
In comparison, a matching group of study volunteers who took only an inactive placebo pill did not change by these measures.
"Personality, a set of traits and attributes that characterize individuals and that persist throughout life, has been thought to be about fifty to sixty percent attributable to inheritance, a conclusion based in large part on studies of twins reared either together or apart," Reus explains.
"Inherited aspects of personality by definition must have some biological underpinning, but this is the first controlled study of the effects of a drug on a component of personality in people who are not mentally ill," he says. "Our findings lead us to conclude that different aspects of normal personality may be altered by psychopharmaceuticals that act on distinct nerve pathways in the brain."
Other researchers in previous studies found that, in psychiatric patients, low
levels of a signaling molecule, the neurotransmitter serotonin, may be related
to psychiatric disorders characterized by hostility and aggression, Reus
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