Serotonin and externalizing behavior in young children

Considerable evidence suggests that there is a relationship between patholo gic aggressive behavior and low cerebrospinal fluid (CSF) concentrations of the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) in both human s and non-human primates. The purpose of this investigation is to examine t he relationship between CSF concentrations of human newborn 5-HIAA and subs equent aggressive behavior observed at 30 months of age. Leftover portions of culture negative CSF drawn from febrile infants (age, birth to 3 months) were assayed for 5-HIAA. Family environment and child behavior were assess ed at 30 months by parent report. Subjects with 5-HIAA levels below the med ian of the distribution had higher externalizing behavior scores at 30 mont hs than did subjects whose 5-HIAA levels fell above the median (P = 0.02). While it is likely that serotonin mediates one component of genetic liabili ty to antisocial outcome, the magnitude of that component may be less than what has been inferred from previously published reports. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.