The electroencephalogram in Alzheimer-type dementia. A sequential study correlating the electroencephalogram with psychometric and quantitative pathologic data.

As part of a longitudinal cohort study of dementia, 139 patients with Alzheimer's disease (dementia of the Alzheimer type, senile dementia of the Alzheimer type, and mixed type [ischemic score, 4 to 7]) and 148 age-matched control subjects were evaluated for electroencephalographic (EEG) abnormalities and their evolution. Electroencephalograms were significantly different in the two groups; EEGs worsened overall in the two groups during a period of one to four years, but most subjects showed no alteration in their EEGs. Some patients showed improvement in their EEG findings during the follow-up period. A strong correlation between EEG grade and psychometric scores was consistently found over sequential studies. In a subgroup of patients on whom autopsies were performed, morphometric neuron loss correlated significantly with EEG severity.