The Roles of Norepinephrine and Serotonin in Attention Deficit Hyperactivity Disorder

The influence of serotonin- and other genes on impulsive behavioral aggression and cognitive impulsivity in children with attention-deficit/hyperactivity disorder (ADHD): Findings from a family-based association test (FBAT) analysis

“…The genes were selected because their expression affects 5-HT activity and closely-related neural functions and they have previously been reported to be associated with a diagnosis of ADHD. The focus on 5-HT-related features was based on descriptions of the relevance of this transmitter to the expression of impulsivity [ 4 , 26 , 53 ] and for the preferential transmission of polymorphisms influencing 5-HT function in ADHD (see introduction). Gene-wide significance was achieved only for a variant of the gene encoding the enzyme for the synthesis of adrenalin (PNMT) in cognitive impulsivity.…”

“…There is mounting evidence that polymorphisms for genes influencing several features of the 5-HT system are associated with ADHD [4], and a case has been made for a differential involvement of 5-HT activity in impulsive aggressive behavior and cognitive impulsivity [26]. For example, in one study increases of platelet 5-HT transporter affinity in 20 children with ADHD correlated with ratings of externalizing behavior, but decreases of affinity were associated with distractibility, impulsivity and the difficulty to withhold a prepotent response on the stop-task [27].…”

“…The goal of the current study is to disentangle the relationship between aggressive impulsivity of a more behavioral nature and cognitive impulsivity in ADHD by exploring the differential patterns of association of these two forms of impulsivity with genes that have significance for 5-HT function, a putative neurobiological marker of impulsivity. There is mounting evidence that polymorphisms for genes influencing several features of the 5-HT system are associated with ADHD [ 4 ], and a case has been made for a differential involvement of 5-HT activity in impulsive aggressive behavior and cognitive impulsivity [ 26 ]. For example, in one study increases of platelet 5-HT transporter affinity in 20 children with ADHD correlated with ratings of externalizing behavior, but decreases of affinity were associated with distractibility, impulsivity and the difficulty to withhold a prepotent response on the stop-task [ 27 ].…”

Methylphenidate effects in attention deficit/hyperactivity disorder: electrodermal and ERP measures during a continuous performance task

“…This model also accounts for the seemingly paradoxical effect of stimulant medications on the behaviours of AD/HD children; in small doses, stimulants act to increase their arousal to normal levels, which results in reduction of the problem behaviours. In a recent review, Oades (2005) reports biochemical support for the concept of hypoarousal in AD/HD from measures of adrenaline and phenylethylamine. Previous research has shown that adrenaline levels tend to be low in urine samples from AD/ HD children, and accordingly, the adrenergic response to stress is reduced (Hanna et al 1996).…”

Electrophysiology in attention-deficit/hyperactivity disorder

“…In addition to the much-publicised consequences of hypofunction in the dopamine system in AD/HD, the authors put forward a role for the serotonin and noradrenaline systems. This is of interest in view of a recent general increase in the awareness of the potential contribution of these other monoamines to the wider clinical picture (see review by Oades, 2005). Exploration of the different pathways elucidated in the model should provide a rich source of hypotheses regarding the effectiveness of various medications (both stimulant and non-stimulant), and other treatments such as EEG biofeedback training, in the two EEGdefined subgroups.…”