EEG spectral profile to stage Alzheimerʹs disease

Objective:The present study was undertaken to investigate whether a synoptic parameter of quantitative EEG (qEEG), such as the power spectral profile, may be used as a simple marker to stage Alzheimerʹs disease (AD) in the clinical setting. Methods:To this purpose, the qEEG spectral profile was examined in 48 patients (mean age: 73 years) with probable (NINCDS-ADRDA criteria) AD, who were divided into 4 groups, according to the Global Deterioration Scale (GDS; score: 3–6). The spectral profile of each patient was expressed by the relative power of seven frequency bands (2–3.5, 4–5.5, 6–7.5, 8–9.5, 10–11.5, 12–13.5, 14–22.5 Hz). Mean values in each of the four GDS groups as well as in a control group of 18 healthy elderly subjects underwent multivariate analysis of variance. Results:A normally shaped but shifted-to-the left spectral profile was found in GDS 3 group, whereas a reduced background rhythm with various increase in slow activity power characterized both GDS 4 and 5 groups. Finally, an ‘exponential asymptotic’ profile with the highest power in the lowest frequencies was the hallmark of GDS 6 group. Overall, the 4–5.5 Hz and the 10–11.5 Hz band powers showed the highest statistical significance in differentiating the patient groups between one another and from controls (P<0.0001). Conclusions:These data show that spectral profile is a very simple parameter which can be used to stage the disease on a pathophysiological basis.