Vol. 5, No. 1, 1999 Page 5 
|
Vol. 5, No. 1, 1999 Page 5 |
The apparent link between aggression and low levels of serotonin is now well known (see related article, Crime Times, 1998, Vol. 4, No. 2, Page 1). But a new study indicates that high levels of another neurotransmitter, vasopressin, may also play a role in human aggression.
Several animal studies have linked high vasopressin levels to increases in aggressive behavior. In golden hamsters, for instance, injection of arginine vasopressin (AVP) into the hypothalamus increases the number of biting attacks on intruders. Administra ation of a drug that stops AVP from binding to receptors in the brain, conversely, inhibits offensive aggression. Other studies have also linked high AVP levels to aggression in rats and in male voles.
Intrigued by these findings, Emil Coccaro et al. investigated vasopressin levels in human subjects. The researchers studied 26 personality-disordered males and premenopausal females. Subjects' histories of aggression were determined using the Life History y of Aggression assessment.
The researchers report that the cerebrospinal fluid AVP levels of their subjects correlated directly with a life history of general aggression, and particularly with a history of aggression against persons. As expected, serotonin system functioning appear red to correlate inversely with aggression. However, Coccaro et al. note that AVP levels "accounted for a significant and unique proportion of the variance in life history of aggression scores even after the influence of [serotonin function] was accounted d for." Thus, they say, "central AVP may play an important role in aggression on its own."
The researchers note that the correlation between aggression and AVP levels was seen in both male and female subjects. However, the relationship was much stronger for males. This finding is interesting, Coccaro and colleagues say, in light of research sho owing that AVP administration does not lead to increased aggression in castrated male hamsters deprived of testosterone. "Accordingly," they say, "our findings may reflect a real sex difference in the relationship between central AVP and aggression in hum m mans."
Citing research showing that a drug-induced increase in serotonin levels leads to a marked drop in AVP and aggressive behavior in hamsters, Coccaro and colleagues speculate that the anti-aggressive effects of serotonin reuptake inhibitors such as Prozac " may be mediated in part by a [serotonin] effect on central AVP."
"Cerebrospinal fluid vasopressin levels. Correlates with aggression and serotonin function in personality-disordered subjects," Emil F. Coccaro, Richard J. Kavoussi, Richard L. Hauger, Thomas B. Cooper, and Craig F. Ferris, Archives of General Psychiat try, Vol. 55, August 1998. Address: Emil F. Coccaro, Clinical Neuroscience Research Unit, Department of Psychiatry, MCP-Hahnemann School of Medicine, 3200 Henry Avenue, Philadelphia, PA 19129.