Frontal, temporal and lateralized brain function in children with attention-deficit hyperactivity disorder : a psychophysiological and neuropsychological viewpoint on development.
Introduction: This review considers deficits in the selective aspects of perception (i.e. attention) underlying symptoms of impaired attention and impulsivity in children with attention-deficit hyperactivity syndrome (ADHD) in terms of frontal and temporal lobe function and cerebral asymmetry. Review: Tomographic studies suggest a disturbance of fronto-striatal function, but have neglected limbic contributions under activating conditions and are contradictory or equivocal on the nature of apparent lateralised differences of structure. Functional neuropsychological (e.g. go/no-go and covert orienting of attention tasks) and psychophysiological studies (e.g. event-related potentials and mismatch negativity ) suggest that early and late stages of information processing are affected in both the frontal and temporal lobes. Performance differences in young ADHD patients imply an impairment in the inter-cortical dialogue. Given the evidence for a normal specialisation in global processing in the right and the processing of details in the left hemisphere, the lateralised impairment may progress from situational ADHD (resulting in impaired selective aspects of perception on the right) to pervasive ADHD (inducing an additional impairment in decision making on the left: compare risk taking). Conclusions: Accordingly a proportion of ADHD children may experience an early negative neurodevelopmental influence that only appears as the brain region matures (especially around 8-12 years of age) while others show an independent, longer term, delayed development of CNS function.