Introduction: Attention deficit disorder with or without hyperactivity (ADHD) is characterised by the patients' inability to pay attention in non selective activities, hyperactivity that is difficult to inhibit, impulsiveness with failure to control their reactions and an unstable personality, which gives rise to difficulties in learning, work, leisure activities and in the social milieu, and may get worse in unstructured settings. There is a clear predominance in males and a 57% possibility of inheritance. The biochemical causes underlying ADHD are unknown, although it is currently accepted that dopamine and noradrenaline release is reduced because of the positive response to methylphenidate (MPH) and other stimulants.
Aims: The aim of this study was to evaluate the response to immediate release MPH by combining clinical data based on the DSM IV and brain mapping and quantitative electroencephalogram studies (qEEG).
Patients and methods: We conducted a study of 170 otherwise pathology free children with a 5 to 1 predominance of males and an average age of 8 years old. Patients' records were examined and a hemogram and general biochemical analysis were carried out together with tests to determine thyroid hormone and cortisol levels, and BM CEEG. In addition, 46 children were submitted to a nocturnal polysomnogram (nPSG).
Results: A third of the children presented associated pathologies such as allergic rhinitis, asthma, allergies and dermatitis, with no differences between sexes. Paroxysmal discharges were revealed by the nPSG in 16.7% and there was a general agreement between answers provided by families and teachers. In the qEEG the most striking data was the theta/alpha quotient, which showed a medium degree of generalised dominance of the theta band (but no correlation with age) in 49.9% and it was mild in 5.9%. Following a year's treatment, there was an overall, not focal, improvement in activity, mild dominance rose to 58.2% and the others fell 2.4%. The other traces were unspecific. Clinical progression was good in 78.2% of cases, 19.5% of mild complications being resolved by lowering the drug dosage or by withdrawing it altogether.
Conclusions: 1). ADHD is more likely to remain into adulthood and it has been associated to immunological disorders or epileptiform paroxysms, although only in a minority of cases. 2). The effect of MPH can be objectified by serial recordings of digitised cortical bioelectrical activity, with synchronised progression of the clinical response.