Serial EEG in Alzheimer's disease: 3 year follow-up and clinical outcome

We describe EEG findings and clinical outcomes of 24 Alzheimer (AD) patients over a 3 year follow-up period. Three records, baseline, 1 year and 3 year, were available for 13 patients. Although the majority of the patients showed slowing of the EEG over 3 years, evolutions of the EEG changes were not equal in all patients. In 12 (50%) of the patients the EEG from T6-O2 derivation was normal or slightly abnormal in the initial record and remained stable during 1 year. At year 3, only 2 patients still had normal EEGs and mild dementia, probably representing a subgroup of AD with a benign course, 7 patients needed institutional care and 3 had died. EEG slowing at the time of diagnosis was predictive of poor outcome at year 3; absolute theta amplitude was the best discriminating variable of outcome. The results support the idea of heterogeneity of AD patients and suggest that EEG may provide valuable information for prediction of outcome.