Reduction of (³H)-imipramine binding sites on platelets of conduct-disordered children

Binding characteristics of tritiated imipramine on blood platelets were determined in daytime hospitalized prepubertal children who had mixed diagnoses of conduct disorder (CD) plus attention deficit disorder hyperactivity (ADDH) and in inpatient adolescents who had a history of aggressive behavior. The number of (³H)-imipramine maximal binding sites (B_max) was significantly lower in the prepubertal patient group of CD plus ADDH; the dissociation constant (K_d) was not significantly different. There were significant negative correlations between B_max and the Externalizing or Aggressive factors of the Child Behavior Checklist when the CD plus ADDH prepubertal patients were combined with their matched controls and within the adolescent inpatient group. We propose that a decreased platelet imipramine binding B_maxvalue, as an index of disturbed presynaptic serotonergic activity, is not specific to depression and may be used as a biologic marker for the lack of behavioral constraint in heterogeneous populations of psychiatric patients.