ADHD - An Illustrated historical overview

Images of the brain D ue to its sensivity to brain me- tabolism, local or generalized blood flow, brain lesions and chemical agents, electroencephalography (EEG) has been used to analyse behaviour disorders throughout the 20 th cen- tury. One of the first relevant contri- butions was a study by the EEG pio- neer Herbert H. Jasper (together with Philip Solomon and Charles Bradley) in 1938 that showed distinctly abnormal electroencephalograms in the major- ity of a group of 71 behaviour prob- lem children from the Emma Pendleton Bradley Home . Further EEG studies (e.g. evoked potentials, brain mapping) also shed light on the effects of psycho- stimulants and revealed that the EEG of ADHD patients is characterized by increased slow and decreased fast ac- tivity (Barry et al. 2003). Along with such new insights, the 1980s saw the deployment of other imaging techniques. Important obser- vations came from Hans Lou and his group, who studied three-dimensional regional cerebral blood flow (rCBF) in children with dysphasia and/or atten- tion deficit disorder by applying Xenon 133 inhalation, a technique pioneered in Scandinavia in the 1960s. In all elev- en patients with attention deficits in the 1984 study, Lou found hypoperfu- sion in the white matter of the frontal lobes, and also hyperperfusion in the caudate region in seven. In a similar study in 1989, Lou and colleagues re- fined their selection of patients and confirmed their previous results. Ad- ditionally, they observed that striatal dysfunctions can be partly reversed with methylphenidate, evidence that low striatal activity is involved in ADHD. Another interesting contribution was a study by Zametkin et al. in 1990. Using positron emission tomography (PET), pioneered in the 1960s by David Kuhl and Roy Edwards, the authors meas- SPM analysis showing a significant decrease of gray matter volume in both occipital lobes. Sagittal, axial and coronar view. Images courtesy of L.T. van Elst, Freiburg, Germany.