[Effect of the time of day on the EEG in cerebral arteriosclerosis]

The study was conducted with three men and seven women, 72-84 years old, characterized by psychopathological and clinical signs of cerebral arteriosclerosis (A). All patients suffered from disorder of sleep-waking rhythm. With one exception every experiment ran for five days during which closed-eye-EEGs were registered at 8 a.m., 12 noon, 4 p.m., and 8 p.m. of the alert but relaxed patients and recorded on tape for computer processing. Simultaneously with every EEG registration the body temperature was measured. The findings were compared statistically with corresponding data of a former study conducted with ten healthy aged volunteers (G).

The dominant peak-frequency of the patients turned out significantly slower than that of the volunteers.--While in healthy persons the peak frequency increased corresponding with the body temperature from the morning to the late afternoon or the early evening respectively, the patients lacked such a correlation, although their temperatures rose gradually in the normal way. In most of the patients the peak-frequency had a remarkable small variety from day to day as well as from scalp-position, and its circadian shift was poor. Psychopathologically these subjects manifested primarily memory loss, general intellectual decline, and in four cases disorientation. On the other hand the EEGs of three women showed substantial greater variety of the peak-frequency from day to day and from scalp-position to scalp-position. Besides the alterations during the day were rather excessive, but lacking any appreciable correspondence with the undisturbed circadian variations of the body temperature. In these three cases psychopathologically personality changes preponderated.