Vol.:(0123456789) 1 3 Aging Clin Exp Res DOI 10.1007/s40520-017-0814-8 ORIGINAL ARTICLE Non-amnestic mild cognitive impairment and sleep complaints: a bidirectional relationship? Luca Rozzini 1,2  · Marta Zaffira Conti 1  · Maddalena Riva 1  · Anna Ceraso 1  · Salvatore Caratozzolo 1  · Marina Zanetti 1  · Alessandro Padovani 1   Received: 7 June 2017 / Accepted: 2 August 2017 © Springer International Publishing AG 2017 Keywords Sleep disorders · Mild cognitive impairment · Alzheimer disease · Daytime sleepiness · Dementia · Neuropsychological characteristics Introduction Normal aging is linked to several changes in the continu- ity and architecture of sleep, as well as in the circadian sleep–wake pattern: older people experience longer sleep latency, reduced total sleep time and efficiency and more fragmented sleep compared to young and middle-aged adults [1]. Furthermore, a strong bidirectional relationship between sleep disturbances and cognitive decline has been proven [2], since disturbed sleep represents both a consequence of brain atrophy and an element of cognitive decline’s patho- genesis [3]: disruption of sleep–wake rhythm’s neural regu- lation appears to be involved in the molecular mechanisms of cognitive decline [2] and sleep disturbances seem indepen- dently associated with increased risk of incident cognitive impairment [4]; moreover, multiple sleep disorders—includ- ing insomnia, REM behavior disorders (RBD), sleep-disor- dered breathing (SDB), restless legs syndrome (RLS), and excessive daytime sleepiness (EDS)—frequently occur in patients with neurodegenerative and vascular dementia or mild cognitive impairment (MCI) [5]. Some neurodegenera- tive conditions, such as synucleinopathies and tauopathies, primarily induce sleep disorganization or exacerbate age- related changes [6, 7]. Nevertheless, sleep disturbances are often underestimated and not systematically investigated in clinical settings [2]. Among Alzheimer’s disease (AD) patients, sleep disor- ders have a prevalence range of between 24.5–40% and seem to correlate with the severity of cognitive impairment [3], Abstract Background Prior studies documented that several sleep disorders may coexist in patients affected by Mild Cognitive Impairment (MCI) and Alzheimer disease (AD), and have a strong bidirectional relationship with cognitive decline. Aim To assess the self-reported sleep quality and daytime sleepiness among subjects affected by MCI and AD at early- stage and healthy controls, and to verify if sleep disturbances might be an indicator of specific cognitive deficits. Methods 139 patients (102 MCI, 37 AD) underwent com- prehensive neuropsychological, functional, and behavio- ral assessment, which also included Epworth Sleepiness Scale (ESS) and Pittsburgh Sleep Quality Index (PSQI). 80 healthy elderly subjects were used as controls. MCI patients have been divided into Good Sleepers and Bad Sleepers, depending on their reported sleep quality (PSQI global score ≤5/>5). Results MCI patients experienced more subjective day- time sleepiness than AD matches. As for the subjective sleep quality among MCI patients, 54% of Bad Sleepers met diagnostic criteria for non-amnestic MCI; vice-versa, 73% of Good Sleepers were diagnosed with amnestic-MCI (p = 0.005), independently of depression and anxiety. Conclusions MCI patients complain of daytime sleepi- ness and dysfunction more than AD patients; among MCI patients, Bad Sleepers appear mainly characterized by a non- amnestic cognitive profile. * Luca Rozzini lrozzini@iol.it 1 Department of Clinical and Experimental Sciences, University of Brescia, Piazzale Spedali Civili, 1, 25100 Brescia, Italy 2 Geriatric Research Group, Brescia, Italy