Some quantitative EEG findings in unmedicated and medicated major depressives.

To confirm previous quantitative EEG findings in major depressive disorder and to assess effects of medication, EEGs were recorded under eyes closed and open conditions in 68 patients (34 unmedicated and 34 medicated) and nonpatients matched for age and sex. Time series analyses of amplitude, frequency and wave symmetry were performed; differences between eyes open and closed were adjusted for eyes closed values to obtain measures of reactivity. These reactivity measures yielded the main differences between unmedicated patients and nonpatients; depressives were more reactive. Reactivity differences were eliminated or reversed in medicated patients. The EEGs of unmedicated depressives appear to be overreactive, while medications decrease EEG reactivity.