Relationships between psychiatric diagnosis and some quantitative EEG variables.

Psychiatric diagnostic correlates of EEG measures were investigated in 242 unmedicated patients and 94 nonpatients. Computer analysis of eyes-open and eyes-closed EEGs (12 leads) provided time series of amplitude, frequency, and wave-symmetry measures; mean levels and temporal variability indexes were also factor analyzed across leads. Comparisons between various age- and sex-matched groups disclosed numerous differences. Compared with those of nonpatients, schizophrenics' EEGs showed lower amplitude variability, greater frequency variability, greater wave symmetry, and less reactivity to eye opening. The EEGs of schizophrenic subgroups, including latent schizophrenics, were similar and also like those of manics. The EEGs of manics and major depressives differed markedly. The EEGs of subjects with personality disorders and schizophrenics differed from nonpatients in opposite directions. Groups could be classed according to the level of EEG activation: high included manics and schizophrenics; normal, nonpatients and neurotics; and low, major depressives and those with personality disorders.