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Oades, R. D., (2008). Introduction: Poor control of attention-related
and motor processes, often associated with behavioural or cognitive
impulsivity, are typical features of children and adults with attention-deficit
hyperactivity disorder (ADHD). Until recently clinicians
have observed little need to improve on or add to the catecholaminergic - 1 - Genetic studies imply that for both DA and 5-HT systems variants may frequently occur in ADHD for neurotransmitter uptake, synthesis and breakdown functions. - 2 - The separate distributions in the brain of mesolimbic DA transporter and mesocortical DA D4 binding sites, both strongly implicated in ADHD, draws attention to potentially differential contributions from the 5-HT system. However, the evidence here points less towards an anatomical differentiation, as towards one in terms of inhibitory/facilitatory pre/post-synaptic location of receptors in the 5-HT1 and 5-HT2 families. - 3 -
While the monoamine
metabolite levels excreted in ADHD are often correlated, this may well
flow from a starting point where 5-HT activity
is - 4 - It appears that perhaps both situations may arise reflecting different diagnostic subgroups of ADHD, and where impulsive characteristics of the subjects reflect externalizing behaviour or cognitive impulsivity. - 5 - For these features there is clear evidence that DA and 5-HT neuronal systems can and do interact anomalously in ADHD - at the level of the soma, the terminals and at a distance. - 6 - Interactions mediated by macroglia are also likely. However, it remains difficult to ascribe specific mechanisms to their effects (in potentially different subgroups of patients) from this relatively new field of study that has as yet produced rather heterogeneous results. see also Oades, R.D., (2007) Role of the serotonin system in ADHD: treatment implications. Expert Reviews in Neurotherapeutics, 7, 1357-1374. Oades, R. D., (2006) Function and dysfunction of monoamine interactions in children and adolescents with AD/HD. In, "Neurotransmitter interactions and cognitive function". E. D. Levin (Eds.). Birkhäuser Verlag, pp. 207-245. flyer/order form : book contents : chapter Oades, R. D., (2005) The Role of Norepinephrine and Serotonin in ADHD. In: “Attention Deficit Hyperactivity Disorder: From Genes to Animal Models to Patients”, D. Gozal and D. L. Molfese (Eds.), Humana Press, Totawa, NJ: pp.97-130. |