EEG power spectrum differences in early and late onset forms of Alzheimer's disease

Objective: To evaluate the relationship between some EEG spectral parameters and age of onset of Alzheimer's disease (AD). Methods: A study on the wakefulness EEG, recorded during eyes closed and open, was carried out on 150 AD patients (NINCDS-ADRDA criteria). Fifty-two normal subjects served as controls. Results: A significant prevalence of an EEG spectrum characterised by lack of a dominant peak in the 6.5-12 Hz band was found in early AD (EAD). Age of onset correlated inversely with the 1-6.5 Hz relative powers and positively with 6.5-12 Hz relative powers. A similar correlation was also found when a subgroup of mild initial AD was selected. Moreover, evidence of EEG changes peculiar to early onset AD emerged when 3 subgroups (with age of onset less than or equal to 60, range 61-69 and greater than or equal to 70 years) were compared. Conclusion: Irrespective of the severity of disease, this study provides evidence of specific changes of wakeful EEG in patients affected by early-onset AD. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.