[Studies of evoked potentials in children with the syndrome of attention deficit and hyperactivity]

The syndrome of attention deficit and hyperactivity (SADH) is a frequent diagnosis in school children, based on clinical criteria systematized in the DSM-IV and the ICD-10. Nevertheless, there is no biological marker sufficiently sensitive and specific to confirm the diagnosis and clarify the physiopathological mechanism of this disorder of psychological development.

For this, endogenous evoked potentials especially the P300 wave, related to the processes of selective attention and sensory elaboration of discriminatory stimuli, have been used. In order to study the type of alteration in the P300 wave of children diagnosed as having SADH, and the changes induced after two months of treatment with methylphenidate (MF), 12 children were studied. The paradigm of oddball type auditory stimulation was used. The latency and wavelength of the P300 wave at the Cz electrode before (basal) and 2 hours after taking 10 mg of MF were determined. Comparative analysis of the average latencies before and after administration of MF showed significant differences (p < 0.01), with a shortening of the latency following treatment. No significant changes were seen in amplitude. In only two patients (17%) were there no differences in the latency of response before and after treatment, and no response at all to treatment.

These results show the practical usefulness of study of the P300 wave in children with SADH, at least for monitoring the efficacy of pharmacological treatment.