Neurophysiological methods testing the psychoneural basis of attention deficit hyperactivity disorder.

Theories concerning the etiology of attention deficit hyperactivity disorder have evolved from the 1950s, when it was believed that an injury to or dysfunction of the diencephalon was the cause of the syndrome, to the present day, when delayed brain maturation is postulated as an explanation. Delay in laying down myelin can be investigated by newly developed techniques like computerized EEG and transcranial magnetic stimulation. In this study, a group of 15 children 3-7 years of age suffering from attention deficit were investigated using both methods in combination and were compared to a control group of 23 age-matched normal children. On the computerized EEG spectral analysis significant differences to the control group were found in areas O1 and O2 (P < 0.05, Student's t-test). With transcranial magnetic stimulation, the overall difference in right/left stimulation was statistically significant (P < 0.001). The results suggest delayed myelination at the brain stem reticular formation where the alpha rhythm is activated and at the corticospinal pathway as parts of a widespread involvement.