Serotonin, aggression, and parental psychopathology in children with attention-deficit hyperactivity disorder

Objective: To explore the relationship between central serotonergic (5- HT) function and history of parental aggression in aggressive and nonaggressive boys with attention-deficit hyperactivity disorder (ADHD). Method: History of psychiatric symptoms was assessed in the biological parents of 41 boys with ADHD. The relationship between 5-HT function in aggressive and nonaggressive probands, as assessed via the prolactin response to fenfluramine (FEN) challenge, and parental history of aggression was examined. Results: Aggressive boys with a parental history of aggressive behavior had a significantly lower prolactin response to FEN challenge than aggressive boys without a parental history of aggression. Nonaggressive boys had a prolactin response midway between those of the two aggressive subgroups, and their prolactin response did not vary as a function of parental aggression. Children subdivided on the basis of parental history of other psychiatric symptoms did not differ in their response to the FEN challenge. Conclusions: These data indicate an association between parent aggressive behavior and lower 5-HT function in aggressive boys with ADHD but do nor indicate the extent to which this association is environmentally and/or genetically transmitted. There may be different neurochemical mechanisms in familial and nonfamilial aggressive children, which have clinical implications for pharmacological interventions.