Etiology of AD/HD

AD/HD as defined by DSM IV criteria includes a clinical spectrum of disorders which may have multiple etiologies. Common to these disorders is the symptom of inattention. Evidence is accumulating that attention is a neuropsychological function and that disorders of attention are biologically based. Epidemiological data,the modulation of neurotransmitter function by pharmacological interventions and neuroimaging have contributed to the current understanding of this disorder. A model has been proposed for central nervous system pathways which maintain attention.