Author(s): Oades RD, Slusarek M, Velling S, Bondy B
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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.
This article was published in World J Biol Psychiatry
and referenced in Journal of Genetic Syndromes & Gene Therapy