Testosterone and homicidal behavior

To the Editor

Human and animal studies suggest that testosterone may be involved in the pathophysiology of aggressive and violent behavior. Multiple animal experiments have demonstrated that experimentally raising testosterone increases aggressiveness. In most studies of criminals, higher testosterone levels have been associated with violence. For example, serum testosterone levels were examined in about 200 15–17-year-old male criminal offenders (Brooks and Reddon, 1996). Violent offenders had significantly higher testosterone levels compared to non-violent or sexual offenders. Testosterone may also increase aggression in females. For example, in women prison inmates, higher testosterone levels are associated with higher levels of criminal violence and aggressive dominance.

Homicides are committed disproportionally by young males. The reasons for this are not clear but many researchers suggested that testosterone may play a role. It has been shown that among prisoners who committed homicide, those who had higher testosterone levels more often knew their victims and planned their murders ahead of time (Dabbs et al., 2001). The authors of this study suggested that their results imply ruthlessness among inmates with higher testosterone concentrations and that homicide more than other violent crimes may bear on issues related to testosterone.

There are several case reports in the literature suggesting a link between the use of testosterone or other androgen anabolic steroids and homicidal behavior (Pope et al., 1996). For example, a 16-year-old boy murdered his 14-year-old girlfriend while using anabolic steroids (Pope et al., 1996). Another case report described a man who beat his wife to death while taking steroids (Pope et al., 1996). Several years ago, a professional wrestler, who killed his wife and son in their home before hanging himself, had extremely high levels of testosterone in his body. In another case, a 19-year-old man shot another man a day or two after he had self-administered a testosterone injection and was probably at the point of peak blood level (Pope et al., 1996).

Possibly, testosterone is involved in the neurobiology of homicide. Future studies on the role of testosterone in the pathophysiology of homicidal behavior are merited and may help to prevent homicides.