Dementia and depression in old age: psychophysiological aspects.

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.