EEG power spectrum differences in early and late onset forms of Alzheimerʹs disease

Objective: To evaluate the relationship between some EEG spectral parameters and age of onset of Alzheimerʹs 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≤60, range 61–69 and≥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.