title: Serotonin platelet-transporter measures in childhood attention-deficit/hyperactivity disorder (ADHD): clinical versus experimental measures of impulsivity.
abstract: Impulsivity in terms of aggression, suicide or poor cognitive control has been associated with low synaptic availability of serotonin (5-HT) in adults and children. However, characteristics of the 5-HT transporter have not been studied in children with attention-deficit/hyperactivity disorder (ADHD: combined type), where impulsivity is a core symptom. Here, we explored in 20 children with ADHD the relationship of the density (Bmax) and affinity (Kd) of the platelet 5-HT transporter measured with [3H]paroxetine to both clinical ratings of impulsivity (Conners' Parent Questionnaire), and an experimental measure of impulsivity (the ability to withhold a prepotent response in the "stop-signal" paradigm). Decreases of affinity (increased Kd) correlated with a low probability of response inhibition, but not with the clinical ratings of impulsivity. However, ratings of distractibility and impulsivity correlated with the experimental measure of response-inhibition. In contrast, increased transporter affinity (low Kd) correlated modestly with higher ratings of aggressive and externalising behaviour. Bmax was not associated with any behavioural score. We conclude that the synaptic availability of 5-HT is under the control of the 5-HT transporter binding site affinity and that low affinity may be related to cognitive impulsivity (distractibility). Increased affinity of the transporter may also be related to conduct disturbance.
authors.affiliation: University Clinic for Child and Adolescent Psychiatry, Essen, Germany. oades@uni-essen.de
authors.forename: Robert D
authors.initials: RD
authors.lastname: Oades
authors.forename: Michael
authors.initials: M
authors.lastname: Slusarek
authors.forename: Silke
authors.initials: S
authors.lastname: Velling
authors.forename: Brigitta
authors.initials: B
authors.lastname: Bondy
mesh_terms: D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis / Q000378:metabolism*; D001665:Binding Sites; D001921:Brain / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism*; D002648:Child; D007174:Disruptive, Impulse Control, and Conduct Disorders / Q000175:diagnosis / Q000378:metabolism*; D006801:Humans; D050486:Serotonin Plasma Membrane Transport Proteins; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires
chemical_list: D002352:Carrier Proteins; D050486:Serotonin Plasma Membrane Transport Proteins