EEG vigilance profile as a supplement of psychiatric data.

A vigilance measurement based on EEG spectra was employed to supplement the clinical data. In an experimental situation when the patient was left undisturbed after a standard stimulation, four typical patterns were observed. Besides the normal profile, a 'somnolent pattern' with pronounced vigilance decrease and an 'unquiet pattern' with high variance could be seen in treated and in untreated schizophrenic patients, respectively. A combination of both characteristics occurred in depressive patients with symptoms such as agitation, tension, and hypochondria. The outcome of treatment was predictable in the patients with a 'mixed pattern', while the drug effect was unpredictable in other patients with the same diagnosis.