| Abstract: | During the past 25 years, researchers have examined the relationship between neurochemical variables and antisocial behavior in human adults, but none has been studied more intensely than the serotonin metabolite 5‐hydroxyindoleacetic acid (5‐HIAA). The goal of the current study was to employ meta‐analytic procedures to quantitatively evaluate selected evidence on the relationship between 5‐HIAA and antisocial behavior. It was expected that antisocial groups would show reduced cerebrospinal fluid 5‐HIAA compared with non–antisocial groups. This study also aimed to assess moderators that could influence the relationship between 5‐HIAA and antisociality. An electronic search and strict inclusion criteria identified 20 reports used in this meta‐analysis. Results showed a significant overall mean effect size (ES = –.45, P < .05) in the direction of lowered 5‐HIAA in antisocial vs. non–antisocial groups. A significant moderating effect for age indicated that groups comprised of antisocial individuals younger than 30 years exhibited larger negative effect sizes (ES = –1.37, P < .05) than groups with older subjects (ES = –.31, P < .05). There were no moderating effects for gender, target of violence, history of suicide, and alcoholism. Age effects may help explain age‐related declines in crime. The fact that effects did not differ based on other moderating variables supports models of reduced serotonin in antisocial individuals, regardless of type of crime or psychiatric problems. Aggr. Behav. 28:299–316, 2002. © 2002 Wiley‐Liss, Inc. |
