Individual analysis of EEG frequency and band power in mild Alzheimer's disease

Abstract

Objective: This EEG study investigates the role of the cholinergic system, cortico-cortical connections, and sub-cortical white matter on the relationship between individual EEG frequencies and their relative power bands.Methods: EEGs were recorded at rest in 30 normal elderly subjects (Nold), 60 mild Alzheimer disease (AD) and 20 vascular dementia (VaD) patients, comparable for Mini Mental State Evaluation scores . Individual EEG frequencies were indexed by the theta/alpha transition frequency (TF) and by the individual alpha frequency (IAF) with power peak in the extended alpha range (5 -14 Hz). Relative power was separately computed for delta, theta, alpha1, alpha2, and alpha3 bands, on the basis of the TF and IAF.Results: Using normal subjects as a reference, VaD patients showed 'slowing' of alpha frequency (TF-IAF) and lower alpha2 power; Mild AD patients showed lower alpha2 and alpha3 power; delta power was higher in both AD and VaD patients; Theta power was higher only in VaD patients.Conclusions: Individual analysis of the alpha frequency and power can discriminate mild AD from VaD and normal elderly subjects.Significance: This analysis may probe pathophysiological mechanisms causing AD and VaD.

Vascular damage and EEG markers in subjects with mild cognitive impairment

“…Based on TF and IAF, we estimated the frequency band range for each subject, as follows: d from TF-4 to TF-2, h from TF-2 to TF, low a band (a1 and a2) from TF to IAF, and high a band (or a3) from IAF to IAF + 2. The a1 and a2 bands were computed for each subject as follows: a1 from TF to the middle point of the TF-IAF range, and a2 from such middle point to the IAF peak (Moretti et al, 2004). We found that the bandwidth in a1 and a2 bands differed among the groups.…”

“…Traditionally, the a power is evaluated in one or two fixed frequency bands ranging from 8 to 13 Hz. Moreover, the analysis of individual EEG frequency bands (Kopruner et al, 1984;Niedermayer, 1993;Klimesch, 1999) could reveal different sub-bands in the range of the a frequency possibly supporting different cognitive functions (Moretti et al, 2004).…”

“…Recently, it has been shown that individual a-frequency markers and spectral power may capture different component (neural) processes, with these two indices discriminating between mild AD and VaD patients (Moretti et al, 2004). The study reported a reduction in EEG a power in AD patients which was not associated with a proportional change in a frequency, whereas patients with VaD, in whom there were diffuse vascular lesions of the white matter, showed a slowing of the a frequency with minor change in the a power.…”

Right ear advantage for vocal communication in frogs results from both structural asymmetry and attention modulation

“…Studies comparing absolute and relative EEG power show that absolute power may yield different results from those obtained using relative power [39][40][41]. Because relative power values exhibit lower group variability than absolute power values and are not affected by the electrical volume conductor properties of the head which influences EEG amplitude [39], relative power is more suitable for comparison between different channels.…”

“…Because relative power values exhibit lower group variability than absolute power values and are not affected by the electrical volume conductor properties of the head which influences EEG amplitude [39], relative power is more suitable for comparison between different channels. For these reasons, average power across epochs in each minute was calculated for each band and overall EEG, respectively.…”