Neurophysiological Assessment of Alzheimer’s Disease Individuals by a Single Electroencephalographic Marker

Article type: Research Article

Authors: Lizio, Roberta^{a; b; 1} | Del Percio, Claudio^{a; 1} | Marzano, Nicola^c | Soricelli, Andrea^{c; d} | Yener, Görsev G.^{e; f} | Başar, Erol^e | Mundi, Ciro^g | De Rosa, Salvatore^g | Triggiani, Antonio Ivano^h | Ferri, Raffaeleⁱ | Arnaldi, Dario^j | Nobili, Flavio Mariano^j | Cordone, Susanna^b | Lopez, Susanna^b | Carducci, Filippo^b | Santi, Giulia^b | Gesualdo, Loreto^k | Rossini, Paolo M.^{a; l} | Cavedo, Enrica^m | Mauri, Margherita^{m; n} | Frisoni, Giovanni B.^{m; n} | Babiloni, Claudio^{a; b; *}

Affiliations: [a] IRCCS San Raffaele Pisana, Rome, Italy | [b] Department of Physiology and Pharmacology, University of Rome “La Sapienza”, Rome, Italy | [c] IRCCS SDN, Naples, Italy | [d] Department of Studies of Institutions and Territorial Systems, University of Naples Parthenope, Naples, Italy | [e] Brain Dynamics, Cognition and Complex Systems Research Center, Istanbul Kültür University, Istanbul, Turkey | [f] Department of Neurosciences, Brain Dynamics Multidisciplinary Research Center, Department of Neurology, Dokuz Eylül University, Izmir, Turkey | [g] Department of Neurology, Ospedali Riuniti, Foggia, Italy | [h] Department of Clinical and Experimental Medicine, University of Foggia, Foggia, Italy | [i] IRCCS Oasi, Troina (Enna), Italy | [j] Service of Clinical Neurophysiology (DiNOGMI; DipTeC), IRCCS AOU S Martino-IST, Genoa, Italy | [k] Dipartimento Emergenza e Trapianti d’Organi (D.E.T.O), University of Bari, Bari, Italy | [l] Department of Geriatrics, Neuroscience & Orthopedics, Institute of Neurology, Catholic University, Rome, Italy | [m] LENITEM (Laboratory of Epidemiology, Neuroimaging and Telemedicine), IRCCS Centro “S. Giovanni di Dio-F.B.F.”, Brescia, Italy | [n] Memory Clinic and LANVIE - Laboratory of Neuroimaging of Aging, University Hospitals and University of Geneva, Geneva, Switzerland

Correspondence: [*] Correspondence to: Prof. Claudio Babiloni, PhD, Department of Physiology and Pharmacology “V. Erspamer”, University of Rome “La Sapienza”, P.le A. Moro 5, 00185, Rome, Italy. Tel.: +39 0649910989; E-mail: claudio.babiloni@uniroma1.it

Note: [1] These authors contributed equally to this work.

Abstract: Here we presented a single electroencephalographic (EEG) marker for a neurophysiological assessment of Alzheimer’s disease (AD) patients already diagnosed by current guidelines. The ability of the EEG marker to classify 127 AD individuals and 121 matched cognitively intact normal elderly (Nold) individuals was tested. Furthermore, its relationship to AD patients’ cognitive status and structural brain integrity was examined. Low-resolution brain electromagnetic tomography (LORETA) freeware estimated cortical sources of resting state eyes-closed EEG rhythms. The EEG marker was defined as the ratio between the activity of parieto-occipital cortical sources of delta (2–4 Hz) and low-frequency alpha (8–10.5 Hz) rhythms. Results showed 77.2% of sensitivity in the recognition of the AD individuals; 65% of specificity in the recognition of the Nold individuals; and 0.75 of area under the receiver-operating characteristic curve. Compared to the AD subgroup with the EEG maker within one standard deviation of the Nold mean (EEG-), the AD subgroup with EEG+ showed lower global cognitive status, as revealed by Mini-Mental State Evaluation score, and more abnormal values of white-matter and cerebrospinal fluid normalized volumes, as revealed by structural magnetic resonance imaging. We posit that cognitive and functional status being equal, AD patients with EEG+ should receive special clinical attention due to a neurophysiological “frailty”. EEG+ label can be also used in clinical trials (i) to form homogeneous groups of AD patients diagnosed by current guidelines and (ii) as end-point to evaluate intervention effects.

Keywords: Alpha rhythms, Alzheimer’s disease, delta rhythms, electroencephalography, low resolution brain electromagnetic tomography (LORETA), neurophysiological assessment

DOI: 10.3233/JAD-143042

Journal: Journal of Alzheimer's Disease, vol. 49, no. 1, pp. 159-177, 2016