Affiliations: [a] Department of Biomedical Sciences, University of Foggia, Foggia, Italy | [b] Casa di Cura San Raffaele Cassino, Italy | [c] IRCCS San Raffaele Pisana, Rome, Italy | [d] A.Fa.R., Dip. Neurosci. Osp. FBF; Isola Tiberina, Rome, Italy | [e] IRCCS “S. Giovanni di Dio-F.B.F.”, Brescia, Italy | [f] Dept of Neurology, IRCCS Oasi Institute for Research on Mental Retardation and Brain Aging (IRCCS), Troina-Italy | [g] Neurol. University “Campus Biomedico” Rome, Italy
Correspondence:
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Correspondence to: Prof. Claudio Babiloni, Ph.D, Department of Biomedical Sciences, University of Foggia, V.le Pinto, 1 71100 Foggia, Italy. Tel.: +39 0881 713276; Fax: +39 0881 711716; E-mail: c.babiloni@unifg.it.
Abstract: Cortical sources of resting eyes-closed alpha rhythms are typically abnormal in mild cognitive impairment (MCI) and Alzheimer's disease (AD) subjects. Here we tested the hypothesis of a progressive impairment of cortical alpha reactivity to eye-opening across amnesic MCI and mild AD subjects, reflecting another aspect of the impairment of cortical neural synchronization. Resting electroencephalography (EEG) data were recorded in 36 normal elderly subjects (Nold), 91 amnesic MCI, and 31 mild AD subjects during eyes-closed and -open conditions. EEG sources were estimated by LORETA software. In the eye-closed condition, posterior alpha 1 (8–10.5 Hz) sources were lower in MCI and AD than Nold subjects. The opposite was true for occipital delta sources (2–4 Hz). Reactivity to the eyes-open condition showed posterior alpha 1 and alpha 2 (10.5–13 Hz) sources was high in the Nold, intermediate in the MCI, and low in the AD subjects. Furthermore, occipital alpha 1 reactivity across MCI and AD subjects was correlated to the cognitive impairment as revealed by Mini-Mental State Examination score. In conclusion, at least at group level, the continuum across amnesic MCI and mild AD status is related to an impaired reactivity of cortical neuronal synchronization to eyes opening at alpha rhythms.
