EEG findings in dementia with Lewy bodies and Alzheimer's disease.

OBJECTIVES To evaluate the role of the EEG in the diagnosis of dementia with Lewy bodies (DLB). METHODS Standard EEG recordings from 14 patients with DLB confirmed at postmortem were examined and were compared with the records from 11 patients with Alzheimer's disease confirmed at postmortem RESULTS Seventeen of the total of 19 records from the patients with DLB were abnormal. Thirteen showed loss of alpha activity as the dominant rhythm and half had slow wave transient activity in the temporal lobe areas. This slow wave transient activity correlated with a clinical history of loss of consciousness. The patients with Alzheimer's disease were less likely to show transient slow waves and tended to have less marked slowing of dominant rhythm. CONCLUSIONS The greater slowing of the EEG in DLB than in Alzheimer's disease may be related to a greater loss of choline acetyltransferase found in DLB. Temporal slow wave transients may be a useful diagnostic feature in DLB and may help to explain the transient disturbance of consciousness which is characteristic of the disorder.