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UBC Theses and Dissertations

Plasma serotonin and psychopathy Newlove, Theresa Anne


It has been consistently demonstrated that reduced serotonergic activity plays a mediating role in the manifestation of aggression regardless of psychiatric diagnosis or personality disorder classification. Specifically, decreased serotonin functioning is associated with irritable and impulsive aggression.The nature and degree of violence exhibited by individuals with diminished serotonergic activity is remarkably similar to thebehaviour exhibited by psychopaths. However, no study to date has directly examined either central or peripheral indices of serotonergic functioning in a defined group of psychopaths. The present study was an examination of plasma 5-hydroxyindolaceticacid (5-HIAA) and plasma serotonin (5-HT) levels in incarcerated males (n=54). Assessment of psychopathy was made using the psychometrically validated Hare Psychopathy Checklist-Revised (PCL-R). PCL-R Factor 2 (a measure of social deviance) and the interaction between Factor 1 (interpersonal/affective) traits and Factor 2 were significantly correlated with plasma 5-HT and 5-HIAA concentrations, respectively. When the level of violence in the index crime (i.e. crimes resulting in death of the victim) was controlled for, psychopaths tended to have higher plasma 5-HIAA concentrations than did their nonpsychopath counterparts. The results are consistent with findings in the literature and are discussed in terms of the etiology of the psychopathic personality.

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