Psychopathic offenders are amoral, shallow, remorseless, impulsive, narcissistic, and lacking in empathy. Previous studies have revealed abnormalities in the brain structure of criminals with these traits (see related articles, Crime Times, 2001, Vol. 7, No. 2, Page 1 and Crime Times, 2000, Vol. 6, No. 2, Page 1), and a new study offers strong evidence of biochemical anomalies in psychopaths who are aggressive.
Henrik Soderstrom et al. recently studied 28 violent and sexual offenders (27 males and 1 female) between the ages of 18 and 45. The researchers measured cerebrospinal fluid (CSF) concentrations of homovanillic acid (HVA, a metabolite of dopamine), and 5-hydroxyindo- leacetic acid (5-HIAA, a metabolite of serotonin), noting that "the ratio between the metabolites of serotonin and dopamine is highly constant, and an increased HVA:5-HIAA ratio indicates an impaired serotonergic modulation of dopamine activity."
The researchers found that high ratios of HVA to 5-HIAA were strongly associated with psychopathic traits, and in particular with behavioral traits such as impulsivity, irresponsibility, aggression, and need for stimulation. In addition, a high ratio of HVA to 5-HIAA was associated with a history of childhood hyperactivity or conduct disorder.
Soderstrom et al. say their findings suggest a high turnover of dopamine in the brains of aggressive psychopaths, combined with a dysregulation of serotonin. They conclude that "dopamine modulating drugs, alone or in combination with serotonin reuptake inhibitors (or drugs with combined dopamine and serotonin modulating action), might be of interest in treatment of aggressive psychopathy."
"New evidence for an association between the CSF HVA:5-HIAA ratio and psychopathic traits," H. Soderstrom, K. Blennow, A-K Sjodin, and A. Forsman, Journal of Neurology, Neurosurgery and Psychiatry, Vol. 74, 2003, 918-21. Address: H. Soderstrom, Department of Forensic Psychiatry, Box 4024, 422 04 Hisings Backa, Sweden, firstname.lastname@example.org.