Alpha and Theta Rhythms Activity is Associated to Morpho- Structural and Perfusional Modifications in Subjects with Prodromal Alzheimer`s Disease

The increase in EEG alpha3/alpha2 frequency power ratio has been associated with AD-converters subjects with mild cognitive impairment (MCI) as well as a reduction in the regional cerebral blood flow (rCBF).

In this study, the association between alpha3/alpha2 frequency power ratio with rCBF changes in subjects with MCI was evaluated.

The alpha3/alpha2 frequency power ratio was computed in 27 subjects with MCI. Two groups were obtained according to the median values of alpha3/alpha2, at a cut-off value of 1.17. In the groups so obtained, the correlation between brain perfusion and EEG markers was detected.

In the MCI group with the alpha3/alpha2 frequency power ratio above 1.17 as compared to the group with alpha3/alpha2 frequency power ratio below 1.17 there were: 1) a constant trend to lower rCBF values; 2) smaller hippocampal volumes; and 3) higher theta frequency power.

The higher EEG alpha3/alpha2 frequency power ratio individuates two different groups of MCI subjects. A complex interplay between alpha and theta rhythms activity MCI patients is suggested in patients with prodromal Alzheimer`s disease.

Keywords: Alpha rhythm, EEG, MRI, SPECT, Theta rhythm.