Nocturnal Hypoxia and Sleep Fragmentation May Drive Neurodegenerative Processes: The Compared Effects of Obstructive Sleep Apnea Syndrome and Periodic Limb Movement Disorder on Alzheimer’s Disease Biomarkers

Article type: Research Article

Authors: Fernandes, Mariana^a | Chiaravalloti, Agostino^{b; c} | Manfredi, Natalia^a | Placidi, Fabio^{a; d} | Nuccetelli, Marzia^e | Izzi, Francesca^d | Camedda, Riccardo^b | Bernardini, Sergio^e | Schillaci, Orazio^{b; c} | Mercuri, Nicola Biagio^{d; f} | Liguori, Claudio^{a; d; *}

Affiliations: [a] Department of Systems Medicine, Sleep Medicine Centre, University of Rome “Tor Vergata”, Rome, Italy | [b] Department of Biomedicine and Prevention, University of Rome “Tor Vergata”, Rome, Italy | [c] IRCCS Neuromed, Pozzilli, Italy | [d] Neurology Unit, University Hospital of Rome “Tor Vergata”, Rome, Italy | [e] Department of Clinical Biochemistry and Molecular Biology, University of Rome “Tor Vergata”, Rome, Italy | [f] IRCSS Santa Lucia Foundation, Rome, Italy

Correspondence: [*] Correspondence to: Claudio Liguori, MD, PhD, Sleep Medicine Centre, Department of Systems Medicine, University of Rome “Tor Vergata”, Via Montpellier 1, 00133, Rome, Italy. Tel.: +39 0620902107; Fax: +39 0620902116; E-mail: [email protected].; ORCID: https://orcid.org/0000-0003-2845-1332

Abstract: Background:Sleep disorders may cause dysregulation in cerebral glucose metabolism and synaptic functions, as well as alterations in cerebrospinal fluid (CSF) biomarker levels. Objective:This study aimed at measuring sleep, CSF Alzheimer’s disease (AD) biomarkers, and cerebral glucose consumption in patients with obstructive sleep apnea syndrome (OSAS) and patients with periodic limb movement disorder (PLMD), compared to controls. Methods:OSAS and PLMD patients underwent 18F-fluoro-2-deoxy-D-glucose positron emission tomography (18F-FDG PET), polysomnographic monitoring, and lumbar puncture to quantify CSF levels of amyloid-β42 (Aβ42), total tau, and phosphorylated tau. All patients were compared to controls, who were not affected by sleep or neurodegenerative disorders. Results:Twenty OSAS patients, 12 PLMD patients, and 15 controls were included. Sleep quality and sleep structure were altered in both OSAS and PLMD patients when compared to controls. OSAS and PLMD patients showed lower CSF Aβ42 levels than controls. OSAS patients showed a significant increase in glucose uptake in a wide cluster of temporal-frontal areas and cerebellum, as well as a reduced glucose consumption in temporal-parietal regions compared to controls. PLMD patients showed increased brain glucose consumption in the left parahippocampal gyrus and left caudate than controls. Conclusion:Sleep dysregulation and nocturnal hypoxia present in OSAS patients, more than sleep fragmentation in PLMD patients, were associated with the alteration in CSF and 18F-FDG PET AD biomarkers, namely reduction of CSF Aβ42 levels and cerebral glucose metabolism dysregulation mainly in temporal areas, thus highlighting the possible role of sleep disorders in driving neurodegenerative processes typical of AD pathology.

Keywords: Alzheimer’s disease, amyloid-β , brain glucose consumption, cerebrospinal fluid, positron emission tomography, sleep

DOI: 10.3233/JAD-215734

Journal: Journal of Alzheimer's Disease, vol. 88, no. 1, pp. 127-139, 2022