Attention deficit disorder with hyperactivity (ADDH): the contribution of catecholaminergic activity

Introduction: An attention deficit disorder with hyperactivity in children (ADDH, later known as ADHD) is now recognized in most countries, although diagnostic practices differ. Evidence is presented to show that the two cardinal symptoms of poor attentional performance and a high degree of motor activity may be functionally and causally separate. Psychobiology: Both attentional and motor-activity alterations are temporarily relieved in a proportion of subjects that respond to psychostimulants. Beneficial treatment decreases noradrenergic (NA) metabolism and normalizes variable levels of dopaminergic (DA) metabolism. Clinical and animal models: Parallels are drawn with other clinical syndromes arising from changed catecholaminergic activity (cf. Phenylketonuria, Tourette's syndrome, Lesch-Nyhan syndrome) and with behavioral interpretations of the result of damage to the dorsal noradrenergic bundle and dopaminergic VTA A10 nucleus (an animal model). Biopsychological research directions: Prognosis of ADDH subjects after treatment remains relatively poor. There may be a further defect of neurotransmitter metabolism in the ADDH syndrome. Research strategies are suggested based on the neurobiological correlates of the cognitive style of ADDH subjects and limbic/septal function in the animal model of the spontaneously hypertensive rat (SHR) Topics: 1 . Psychostimulant response ... Catecholamines / Serotonin, 2 . Electrophysiological and behavioral indices 3 . Responses to monoaminergic agents ... Precursors, L-DOPA, amino acids, monoamine oxidase and others: 4 . Clinical comparisons ... Phenylketonuria, Tourette's syndrome, Lesch-Nyhan syndrome: 5 . Models ... spontaneously hypertensive rat, neurobiology of hypertension Noradrenaline (NA), Glutamate (Glu), Neuropeptide Y (NPY) & Angiotensin, Serotonin (5-HT), Dopamine (DA): 6 . Link between behavior and cognition ... the septum and conditioned blocking measures of selective attention