Neurobiologic Factors.
Neurobiologic Factors in conduct disorder have been little studied, but research in ADHD yields some important findings, and this disorder often coexists with conduct disorder. In some children with conduct disorder, a low level of plasma dopamine B-hydroxylase, an enzyme that converts dopamine to norepinephrine, has been found. This finding supports a theory of decreased noradrenergic functioning in conduct disorder. Some conduct-disordered juvenile offenders have high serotonin levels in blood. Evidence indicates that blood serotonin levels correlate inversely with levels of the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) in the cerebrospinal fluid (CSF) and that low 5-HIAA levels in CSF correlate with aggression and violence.