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Sociopaths, suicide and serotonin.

Sociopaths, suicide and serotonin

Receptors are not the only keyhole through which researchers peek at serotonin disorders. Behavioral studies now appear to link flaws in the serotonin system to violent suicide attempts and aggression.

In a study of convicted male murderers, Markku Linnoila of the National Institute on Alcohol Abuse and Alcoholism, working with colleagues within the federal government and at the University of Helsinki in Finland, have uncovered new data linking the impulsiveness of the murders with chronically low levels of a serotonin breakdown product in cerebrospinal fluid. Men who had committed murder without clear premediation had the lowest levels of the breakdown product, known as 5-hydroxyindoleacetic acid, or 5-HIAA. In addition, men who had killed more than once had lower levels of 5-HIAA than did one-time murderers. Linnoila's group describes the findings in the July ARCHIVES OF GENERAL PSYCHIATRY.

In a study of violent offenders and impulsive arsonists, reported in the same issue, Linnoila's team again found abnormally low levels of 5-HIAA. Men in this group who went on to commit additional violent offenses or arson during an average three-year follow-up period after prison release had the lowest levels of 5-HIAA.

Studies measuring 5-HIAA levels in the cerebrospinal fluid of suicide attempters show that individuals who used violent means, such as guns, tend to have lower levels than those who took pill overdoses. Marie Asberg and her co-workers at the Karolinska Institute in Stockholm, Sweden, have reported their findings in several psychiatric journals since 1976. Alec Roy, now at Hillside Hospital in Glen Oaks, N.Y., and his co-workers reported similar findings in 1986 and in a follow-up in the July ARCHIVES OF GENERAL PSYCHIATRY. The research teams conclude that 5-HIAA, as well as a breakdown product of the neurotransmitter dopamine, may serve as a powerful predictor of suicide risk in depressed individuals. In autopsy studies, other investigators have linked low brain concentrations of 5-HIAA to aggression in Alzheimer's patients.

In contrast, notes Thomas R. Insel of NIMH, some studies of people with obsessive-compulsive disorder show that these individuals have slightly higher-than-normal levels of 5-HIAA. Insel says such findings link the impulsive violence of the sociopath with the guilt of the obsessive-compulsive: At opposite ends of the spectrum, both may be victims of a serotonin imbalance.

"Instead of using a categorical approach to treat mental disorders," Insel suggests, "another way may be to focus on some aspect of behavior in a variety of patients, like the amount of guilt or violent activity."

Linnoila cautions that 5-HIAA is only an indirect indicator of serotonin function. Nonetheless, he and others hypothesize that a deficiency in serotonin metabolism may cause an inability to control impulses, leading to violent behavior. Linnoila says it's too early to determine the drug ramifications of his studies or to ascertain which receptors play out the tale of impulse and aggression.
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Author:Cowen, R.
Publication:Science News
Date:Oct 14, 1989
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