Correlation between Regional Cerebral Blood Flow and EEG Upper/Low Alpha Frequency Power Ratio in Mild Cognitive Impairment

Background : several biomarkers have been proposed for detecting AD in its earliest stages, that is, in the predementia stage. In an attempt to find noninvasive biomarkers, researchers have investigated the feasibility of neuroimaging tools, such as MR, SPECT as well as neurophysiological measurements using EEG. Moreover, the increase of EEG alpha3/alpha2 ratio has been associated with AD-converters subjects with mild cognitive impairment (MCI). Objective : to study the association of EEG marker with specific cerebral blood flow changes in subjects with MCI Methods : 27 adult subjects with mild cognitive impairment underwent EEG recording and perfusion single-photon emission computed tomography (SPECT) evaluation. The alpha3/alpha2 frequency power ratio was computed for each subject. Two groups were obtained according to the median values of alpha3/alpha2, at a cut-off of 1.17. Correlation between brain perfusion and EEG markers were detected. Results : subjects with higher a3/a2 showed a trendly lower perfusion than low a3/a2 frequency power ratio group. The two groups were significantly different as about the hippocampal volume and correlation with the theta frequency activity. Conclusion : there is a complex interplay between cerebral blood flow, theta frequency activity and hippocampal volume in MCI patients with prodromal Alzheimer's disease, characterized by higher EEG alpha3 /alpha2 frequency power ratio.