ADHD - An Illustrated historical overview

Arvid Carlsson. Nobel laureate in 2000 for his work on the transmitter dopamine. Source: Wikimedia Commons. © Vogler. ing involved in systems required for controlling impulsivity and risk avoid- ance, particularly in forebrain systems; indeed, there is some evidence that the dopaminergic agents employed in ADHD achieve their effect by down- stream effects on noradrenergic trans- mission. Atomoxetine, an inhibitor of noradrenaline re-uptake, is currently employed in some countries in the management of ADHD. Serotonin has long been viewed as being involved in inhibitory pathways which reduce impulsive behaviour. Low brain serotonin levels have been asso- ciated with aggression and suicidal be- haviour in humans. The exact nature of this role remains, however, to be eluci- dated; one of the major problems for investigators is the existence of at least 14 serotonin receptor subtypes, some of which are modulated by catechola- mine transmitters. There are currently no ADHD medications which target serotonergic transmission. Impaired glutamatergic transmission in the pre- frontal cortex has been linked with in- creased impulsivity in animal studies, but has not yet been investigated in humans. By Paul Foley, Sydney, Australia.