Attention deficit/hyperactivity disorder--from brain dysfunctions to behaviour.
This special issue represents an attempt to answer fundamental brain and behaviour issues in attention-deficit hyperactivity disorder (ADHD). The European network on hyperkinetic disorders (Eunethydis) is trying to develop a novel, testable theory of ADHD, giving an account of its causes, its development from brain dysfunctions to behavioural symptoms and co-morbidity and explaining why no current therapy produces long-lasting improvements. The combined insights of the articles presented here suggest that there is no brain damage in ADHD, but hypo-efficient dopamine systems which give rise to neurochemical imbalances. These cause behavioural problems: deficits in sustained attention, overactivity and impulsiveness. Impulsiveness is increasingly being seen as a key characteristic of the disorder. None of these symptoms are necessarily primary, but may be secondary to an underlying deficit in reinforcement processes seen particularly in a greater than normal sensitivity to variations in the timing of stimulus presentation. Other symptoms can also be seen: altered effects of reinforcers, increased behavioural variance and motor co-ordination problems. Medication produces temporary, plastic changes in cellular components like receptors and transduction mechanisms normalising dopamine functions and behaviour. reserved.
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D000328:Adult; D000818:Animals; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis / Q000188:drug therapy / Q000503:physiopathology*; D001921:Brain / Q000187:drug effects / Q000503:physiopathology*; D000697:Central Nervous System Stimulants / Q000009:adverse effects / Q000627:therapeutic use; D002648:Child; D015259:Dopamine Agents / Q000627:therapeutic use; D006801:Humans; D007175:Impulsive Behavior / Q000175:diagnosis / Q000188:drug therapy / Q000503:physiopathology*; D008774:Methylphenidate / Q000009:adverse effects / Q000627:therapeutic use
D000697:Central Nervous System Stimulants; D015259:Dopamine Agents; D008774:Methylphenidate