Neurobiology of ADHD

Abstract

The findings of neuropsychological, neurochemical, genetic and neuroimaging research reviewed in this chapter clearly indicate that ADHD does have a neurobiological basis, although its precise nature remains speculative. Given the complexity of interactions between brain regions and neurotransmitter systems and the heterogeneity of ADHD, it is likely that multiple aetiologies and neurobiological deficits can result in the cognitive and behavioural problems we currently define as ADHD. However, despite conflicting theories and research findings, some consistent characteristics do seem to be emerging. Neuropsychological studies implicate deficits in response inhibition as being a core component of ADHD. Frontal lobe and basal ganglia abnormalities in ADHD have also been related to networks involved in attention. While frontal deficits have been extensively studied and for some time have been concluded to play a major role in ADHD, deficits in posterior brain systems are also suggested by some research findings. Theories of altered dopaminergic and noradrenergic activity in ADHD are consistent with research findings of altered brain structure and brain function in regions innervated by these neurotransmitter systems, in particular the frontal cortex, the basal ganglia and the parietal cortex. Neurochemical and neurofunctional deficits in these regions may give rise to the disinhibition, hyperactivity and inattention that are the core features of ADHD. (PsycINFO Database Record (c) 2012 APA, all rights reserved)(chapter)