Quantitative EEG in elderly patients with Alzheimer's disease and healthy controls

Multichannel (19) EEG were analyzed in 23 female patients with rather advanced late-onset Alzheimer's disease (AD) and compared with 56 age- and sex-matched healthy control subjects. The quantified EEG was correlated with psychometric and clinical variables. The control subjects showed increasing theta activity with age but the EEG changes did not correlate significantly with psychometric features. The AD patients showed highly significant increases in delta and theta activity and decreases in beta activity compared with controls. The EEG changes were most marked over posterior regions of the brain. The individual EEG variables showed a high degree of intercorrelation and an almost complete discrimination between patients and controls was accomplished by taking only the posterior delta activity into account. In a subgroup of 10 patients, in which a Mini Mental test score could be obtained, the score correlated with the relative theta power.