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: This study describes the psychophysiological results of a larger investigation of the clinical, morphological, psychometric and psychophysiological aspects of dementia of the Alzheimer type and depression in elderly patients. Healthy volunteers provided a further measure of control. It was found that widely used clinical rating scales delineated the 3 groups of subjects to a significant degree. The average frequency of the electroencephalogram (EEG), the P2-N2 peak-to-peak amplitude and P3 latency of the auditory evoked potential and a characteristic downward shift of the EEG power spectrum differed significantly between demented patients, depressive patients and normal controls. The higher total power in the EEG of the dementia group did not prove statistically significant, probably because of the small numbers. Other psychophysiological measures such as skin conductance level (SCL) and skin temperature (ST) did not reveal statistically significant differences between the groups. Thus, certain psychophysiological measurements may become valuable in the differential diagnosis of these disorders.
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