Diagnosis and subtyping of depressive disorders by quantitative electroencephalography: IV. Discriminating subtypes of unipolar depression.

Of 216 symptomatic adult depressives who underwent comprehensive inpatient biomedical assessment of their illness, 111 met Research Diagnostic Criteria for primary unipolar depressive disorder. Seventy of these patients were segregated into two groups having different frequency analysis profiles as determined by quantitative electroencephalography (QEEG). The following variables were assessed and tabulated for each of the seventy patients: age and sex; presence of endogenous, nonendogenous or atypical symptoms, cognitive impairment, anxiety, obsessive-ruminative thinking, panic and/or phobic symptoms; abnormalities of the dexamethasone suppression test (DST) and the thyrotropin releasing hormone stimulation test (TRHST). Frequency of occurrence of each variable was compared between groups. Two variables were significant--age and TRHST abnormalities. The patients in group 1, characterized electrophysiologically by beta deficit with or without slow wave excess, were older and had more TRHST abnormalities than the patients in group 2, who were characterized electrophysiologically by having slow wave excess only. The implications of these preliminary findings for objective diagnostic subtyping of depression are discussed.