[The electroencephalogram in advanced age]

Aging, by definition, constitutes a biological process rather than a disease. The resulting functional deficiency in transmitter-metabolism is the basis of deviations in the electroencephalographic patterns. In general, the EEG exhibits greater variability in the old age than in the middle decades. The most important characteristic of the EEG in the aged is a slowing of the alpha-frequency often in association with discontinuity, voltage reduction, and successive disruption of alpha rhythm with passages of curve-flattening and slowing of the dominating rhythms. Such patterns of subvigilant activity can dominate the EEG in the aged under resting conditions. Another common feature of the EEG in older age is an increasing occurrence of theta-waves, especially in the temporal regions. Temporarily, beta-waves increase in frequency in old age--predominantly in the female--usually subsiding by the age of 75. The interpretation of an EEG focus can be difficult in the absence of clinical correlates. In the very old age, the resulting changes in sleep-pattern can be demonstrated in the EEG. EEG and psychic efficiency are related only occasionally; under pathologic conditions, however, the relationship between EEG-anomalies and the intensity of a psychoorganic syndrome demonstrates a closer correlation. Finally, the possibility of gaining new information about psychical activities during aging through the use of evoked potentials is discussed.