Attention deficit hyperactivity disorder

Attention deficit hyperactivity disorder (ADHD), the theme of this issue of Paediatrics & Child Health, is one of the more common and severe childhood disabilities. Its diagnosis and medical management require strong clinical skills and commitment rather than the ability to interpret tests and images. Like all behavioural syndromes it is the product of many different mechanisms, many of which may be present at the same time. Like all other disabilities, it rarely exists alone, requiring the paediatrician to search for other impairments that regularly accompany it. Neuroscience now provides overwhelming evidence that the transactional model of development applies both to neuromaturation and the evolution of behaviour. Neurones and neural networks that are not stimulated succumb to apoptosis or early planned cell death, while networks that are exercised survive and develop interconnections with other networks, producing the integrated, complex, flexible, creative and controlled organism that we associate with successful maturity and self-actualization. The brain learns behaviour. Behaviour teaches and shapes the brain. In some people, a genetic error in hardwiring of left frontostriate and ascending reticular circuitry, or a faulty recipe for an individual's neurotransmitter cocktail, is the cause of the problems. Subtle injuries following premature birth may have similar effects. In the presence of severe maternal depression, which has major effects on the infants brain (1), undesirable behaviours become useful for the baby. A chaotic, unpredictable and inconsistent home environment fails to reward patience and organizational skills, and the neural networks underlying these attributes. A social environment that fails to reinforce a child's capacity for exploration, curiosity, creativity, behavioural inhibition, rule-keeping and a reflective approach also fails to foster the maturation of just those neural circuits and interconnections that are necessary for self-actualization and the enjoyment of all the riches offered by a modern society. The symptoms of ADHD may be made worse by, as well as caused by, depression, anxiety, poor information or language processing (learning disability), adverse life experiences or social confusion. Specific assessment for autistic spectrum disorder is necessary in a substantial minority of children referred as probable ADHD. ADHD is horribly misnamed. No fundamental defect in general attention has ever been demonstrated. All adults and children with ADHD attend well to what interests them, but have no tolerance for boredom. Only half are fidgety and true hyperkinesis is rare. Cognitive neuroscientists identify two basic impairments (2). First, there are deficits in executive function, those activities of the pre-frontal and frontal areas that monitor the consequences of every behaviour initiated and maintained by the brain, providing a continuous quality improvement system for every aspect of motor, social and intellectual performance. Second, there is an inability to condition to or work for delayed rewards. The need for instant gratification and the inability to process either punishment or reward that does not immediately follow the action upon which it is consequent explains the failure of ADHD children to respond to conventional behaviour management and their almost universal ability to excel at computer games that offer feedback that is ongoing and immediate. The symptoms of inattention, impulsivity and hyperactivity seem to be secondary to these major cognitive impairments. Understanding this leads directly into fruitful ways of modifying the child's social and learning environment so that the child can experience success rather than the repeated failures that characterize the lives of most ADHD children. Repeated experiences of failure, and the inability to associate punishment with one's own acts, create avoidance, anger and defiance in a world of which sense cannot be made. In diagnosing ADHD a disability approach is essential. Without strong evidence of a meaningful reduction in quality of life and a handicapping reduction in participation in society (at workplace or school, in family life, in leisure and relationships) all the symptoms listed in the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (3) are irrelevant. Once the disabilities are recognized, we can respond to the needs of the child. In responding to the symptoms alone, rather than to their effects, we are responding only to the needs of the adult world. As in all disabilities, the paediatrician has to work in a multidisciplinary team. This theme issue provides much important information that will help the physician to identify this type of childhood neurobehavioural disability and to differentiate it from the complaints of a dysfunctional adult world whose expectations of children are often inappropriate. Having recognized the areas of functional loss, one can begin to target ways of improving the child's quality of life. Improving the core symptoms will usually help, and stimulants are undoubtedly able to do this whether or not the child has ADHD. The symptom lists are subjective and pay no attention to the age of the child. The Diagnostic and Statistical Manual for Primary Care (DSM-PC) (4) of the American Academy of Pediatrics provides helpful vignettes of the behaviour of children at different ages, and allows the identification of those with normal temperamental traits that mimic ADHD and those whose attentional or impulsive problems are real, but fall short of the severity of a full-blown disorder. DSM-PC is recommended to all who will enjoy and use the information in this theme issue. Meanwhile, I look forward to the day when the name ADHD is forgotten and we call it motivational or organizational skills disorder.

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