EEG findings in senile dementia and normal aging

EEG findings in 62 patients with senile dementia of Alzheimer type (SDA), 22 patients with multi-infarct dementia (MID) and 90 controls of same age and sex were studied. The SDA patients differed significantly from the controls in EEG normality, over-all disturbance, dominant occipital rhythm, accentuation of theta and delta, fluctuations in alertness, paroxysmal activity and H-reaction. Even the least severely affected SDA patients differed significantly from the controls in all EEG variables except paroxysmal activity. With increasing degree of intellectual impairment in the SDA group the dominant occipital rhythm became slower.
The MID group differed from the controls in all EEG parameters including asymmetric findings. The EEG findings of the SDA patients differed significantly from those of the MID patients only in asymmetric findings which were more common in the MID patients.
29 % of the normal elderly people had EEG alterations. Abnormalities were mild. Asymmetric findings, mainly theta activity in left temporal region were common. H-reaction (occipital driving response ± 18 c/s) was well preserved in the controls.
EEG is valuable in differentiation of dementia patients from normal elderly people, but differentiation between MID and SDA is not reliable by using EEG, only.