EEG features of depressive and schizophrenic states

A 25-year-old female patient with a psychotic illness lasting three months in which schizophrenia and depressive episodes occurred was studied by serial EEGs. These were coded, masked and rated in a set way without knowledge of the clinical state. It was found that the schizophrenic state was characterized by a decrease in the amount and poor organization of alpha activity, as well as the occurrence of paroxysmal phenomena in particular a typical spike and wave. In the depressive episode, alpha activity was prominentand only scanty paroxysmal features were seen. Using these criteria a series of EEGsfrom psychiatric patients were assessed 'blind' with a view to separating them into either a schizophrenic or a depressive category. This proved possible in 17 cases (9 depressive and 8 schizophrenic). In only two was the categorization completely misjudged. These results suggest that further detailed study of the EEG, possibly with computer analysis, combined with assessment of the behavioural state might not only yield useful diagnostic information but also lead to a better understanding of the underlying neurophysiological basis of certain mental disorders.