We report EEG findings in 33 elderly patients with mixed symptoms of depression and dementia, followed longitudinally to confirm diagnosis. Two groups of patients, dementia with depressive features (mixed-DEM, group I, n = 23) and patients with depressive pseudodementia (mixed-DEP, group II, n = 10), were defined. In addition, we also included, for comparison purposes, 35 patients with probable AD without depressive features (group III), 23 patients with major depression without cognitive impairment (group IV), and 61 healthy elderly controls (group V). We found significant group differences on waking EEGs between those mixed patients who did well after treatment for depression (depressive pseudodementia) compared to patients having dementia with secondary depression. The differences paralleled those between the 'pure' groups of demented and depressed patients. In patients with either depression or depressive pseudodementia, the EEG was usually normal or showed only mild abnormalities. In contrast, the majority of patients with either dementia or dementia with secondary depression had abnormal EEGs, with approximately one-third having moderate (or severe) abnormalities. Although the EEG was usually normal or only mildly abnormal in patients with pseudodementia or depression, these groups (II and IV) did show a significant slowing of the dominant posterior rhythm compared to controls. They also had a higher percentage of generalized abnormal EEGs than controls and this difference was significant between group IV (depression) and controls.
"The data also suggest that diffuse EEG slowing may be indicative of an underlying organic process in a sicker and less treatmentresponsive group of patients. This possibility is further supported by the q-EEG findings that increased slow activity and decreased mean frequency are correlated with cognitive impairment of organic disorders like Alzheimer's disease (Brenner and others 1989). These 2 possibilities (drug toxicity and organic pathology) are by no means mutually exclusive . "
[Show abstract][Hide abstract] ABSTRACT: Diffuse slowing constitutes 40% of all electroencephalogram (EEG) abnormalities in psychiatric patients. Correlations have been demonstrated between the degree of slowing of the EEG and impairment of functions such as awareness, attention, memory, and comprehension. We conducted the current study in order to determine whether diffuse EEG slowing in hospitalized psychiatric patients correlated with hospitalization indices. Twenty-five patients with diffusely slow EEGs were selected for the study, and 25 patients with normal EEGs were matched to these subjects. Medical records were reviewed for each patient's diagnosis, length of stay, number of medications, and the dosages. Length of stay was significantly longer in the slow EEG group. The number of psychotropic medications used and the dosages of antipsychotic medications were also significantly higher in the slow EEG group. We concluded that the longer length of stay and the increased number of medications and dosages in the slow EEG group may be a reflection of increased illness severity.
[Show abstract][Hide abstract] ABSTRACT: Depressive illness with initial onset after age 60 has different clinical and prognostic features compared to depression beginning at a younger age. We evaluated waking electroencephalograms (EEGs) in 61 elderly depressed patients (32 early onset, 29 late onset) without cognitive impairment and not receiving psychotropic medications. The groups were comparable for age, severity of Hamilton depression score, education, and Folstein Mini-Mental State scores. Conventional visual EEG analysis revealed no significant differences in the mean alpha rhythm, incidence of abnormal records, or types of EEG abnormalities. Computerized spectral EEG analysis was also performed in 48 patients (23 early onset, 25 late onset). There were no significant differences in the pooled parasagittal mean frequency, theta--beta difference, combined delta and theta percentage, or relative power of the frequency bands. Thus, waking EEGs do not differentiate between elderly patients with the initial onset of the depression before or after age 60.
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