ebook_ADHD2019_engl.

88 Rohde, Buitelaar, Gerlach & Faraone DA is actually taken back up by the NA transporter). Clonidine and guanfacine (G) are direct alpha2A receptor agonists; and, therefore, mimic NA action at the postsynaptic alpha2A receptors and improve glutamatergic neurotransmission by reducing ‘noise’ and interference. Dopamine receptors There are two main DA receptors, each of which has different levels of affinity for DA. In ADHD treatment, D1 and D2 receptors are relevant: 1 The D1 receptors have high affinity for DA, and therefore are engaged at relatively low concentrations of DA. At optimal concentration, D1 trans- mission reduces excess activity in the neural network, reducing distractibility and improving concentration. Excessive D1 activity can lead to deterioration in cognitive functions. 2 D2 receptors have a lower affinity with DA than D1 receptors, requiring hi- gher concentrations of DA for activation. At moderate levels of phasic DA neuronal firing, D2 activity enhances reward and motivation, and improves cognitive performance. Some children and adults can be extremely sensitive to D2 activation, this in turn can result in cognitive decline along with emer- gence of agitation, irritability, and paranoia or hallucination symptoms in extreme cases. It is therefore important that stimulant medications are carefully titrated to do- ses that ensure both optimal levels of D1 and D2 activity and continued effective- ness across the course of the day. Over- or under -dosing or marked fluctuation in dose levels across the day can compromise drug response, leading to deterioration of symptoms and cognitive functioning. Link in this http://adhd-institute.com/disease- management/pharmacological- therapy/mode-of-action/