Diagnosis Of Dementia Of The Alzheimer Type Research Articles

Forty Hertz EEG Activity in Dementia of the Alzheimer Type and Multi‐Infarct Dementia

ABSTRACTHigh frequency EEG activity within the 40 Hz band was examined at rest and during two problem solving tasks in patients with presumptive diagnoses of either dementia of the Alzheimer type (DAT) or Multi‐Infarct Dementia (MID), and in normal elderly subjects. The DAT patients differed significantly from normals and MID subjects, exhibiting both decreased rates of 40 Hz EEG activity and no task‐appropriate pattern of cerebral lateralization. Although MID patients did not differ from controls during baseline, significantly less 40 Hz activity was present during performance of a sentence repetition task. Evidence for normal task‐specific asymmetry was present in the MID and control groups. The results suggest that patterns of 40 Hz EEG activity may be of utility in the early diagnosis of DAT. Further, the 40 Hz rhythm appears able to discriminate between patient populations that present with similar patterns of dementia.