Objective Daytime Napping is Associated with Disease Severity and Inflammation in Patients with Mild to Moderate Dementia¹

Article type: Research Article

Authors: Basta, Maria^{a; b; *} | Koutentaki, Eirini^a | Vgontzas, Alexandros^{a; b} | Zaganas, Ioannis^c | Vogiatzi, Emmanouela^c | Gouna, Garyfalia^c | Bourbouli, Mara^c | Panagiotakis, Symeon^d | Kapetanaki, Stefania^c | Fernandez-Mendoza, Julio^b | Simos, Panagiotis^a

Affiliations: [a] Department of Psychiatry, University Hospital of Heraklion, Heraklion, Crete, Greece | [b] Sleep Research and Treatment Center, Department of Psychiatry, Penn State University, Hershey, PA, USA | [c] Department of Neurology, University Hospital of Heraklion, Heraklion, Crete, Greece | [d] Department of Internal Medicine, University Hospital of Heraklion, Heraklion, Crete, Greece

Correspondence: [*] Correspondence to: Maria Basta, Department of Psychiatry, University Hospital of Heraklion, Voutes – Heraklion, Crete, 71110, Greece. Tel.: (+)302810392402; E-mail: mpasta@uoc.gr.

Note: [1] This work has been performed in the Department of Psychiatry, University Hospital of Heraklion, Heraklion, Crete, Greece.

Abstract: Background:Patients with dementia report excessive daytime sleep/sleepiness, which is associated with worse cognitive performance. Inflammatory markers may be elevated in patients with dementia and have been proposed as mediators of sleep/sleepiness. Objective:To examine the association of objective daytime napping with cognitive performance and peripheral markers of inflammation in patients with dementia as compared to not cognitively impaired (NCI) controls. Methods:A sub-sample of 46 patients with mild-to-moderate dementia and 85 NCI controls, were recruited from a large, population-based cohort of 3,140 elders (≥60 years) in Crete, Greece. All participants underwent medical history/physical examination, extensive neuropsychiatric and neuropsychological evaluation, 3-day 24 h actigraphy and a single morning measure of IL-6 and TNFα plasma levels. Comparisons of sleep parameters and inflammation markers between diagnostic groups, and between nappers and non-nappers within each diagnostic group, were conducted using ANCOVA controlling for demographics/related clinical factors. Associations between inflammatory markers, sleep variables, and neuropsychological performance were assessed within each group using partial correlation analysis controlling for confounders. Results:Patients with dementia slept 15 minutes longer during the day than NCI. Within dementia patients, nappers had significantly worse performance on autobiographic memory (p = 0.002), working memory (p = 0.007), episodic memory (p = 0.010), and assessment of daily function (p = 0.012) than non-nappers. Finally, IL-6 levels were significantly associated with nap duration within dementia patients who napped (r = 0.500, p = 0.01). Conclusions:Daytime napping in patients with dementia is associated with worse cognitive performance and increased IL-6 levels. In dementia, objective daytime napping, may be a marker of the severity of the disease.

Keywords: Actigraphy, cognitive performance, cytokines, dementia, inflammation, objective daytime napping

DOI: 10.3233/JAD-190483

Journal: Journal of Alzheimer's Disease, vol. 74, no. 3, pp. 803-815, 2020