title: Depressive Symptoms are the Main Predictor for Subjective Sleep Quality in Patients with Mild Cognitive Impairment--A Controlled Study.
abstract: OBJECTIVE
  Controlled data on predictors of subjective sleep quality in patients with memory complaints are sparse. To improve the amount of comprehensive data on this topic, we assessed factors associated with subjective sleep quality in patients from our memory clinic and healthy individuals.
  
  
  METHODS
  Between February 2012 and August 2014 patients with mild cognitive impairment (MCI) and subjective cognitive decline (SCD) from our memory clinic and healthy controls were recruited. Apart from a detailed neuropsychological assessment, the subjective sleep quality, daytime sleepiness and depressive symptoms were assessed using the Pittsburgh Sleep Quality Index (PSQI), the Epworth Sleepiness Scale (ESS) and the Beck Depression Inventory (BDI-II).
  
  
  RESULTS
  One hundred fifty eight consecutive patients (132 (84%) MCI patients and 26 (16%) SCD patients) and 75 healthy controls were included in the study. Pairwise comparison of PSQI scores showed that non-amnestic MCI (naMCI) patients (5.4 ± 3.5) had significantly higher PSQI scores than controls (4.3 ± 2.8, p = .003) Pairwise comparison of PSQI subscores showed that naMCI patients (1.1 ± 0.4) had significantly more "sleep disturbances" than controls (0.9 ± 0.5, p = .003). Amnestic MCI (aMCI) (0.8 ± 1.2, p = .006) and naMCI patients (0.7 ± 1.2, p = .002) used "sleep medication" significantly more often than controls (0.1 ± 0.6) Both, aMCI (11.5 ± 8.6, p < .001) and naMCI (11.5 ± 8.6, p < .001) patients showed significantly higher BDI-II scores than healthy controls (6.1 ± 5.3). Linear regression analysis showed that the subjective sleep quality was predicted by depressive symptoms in aMCI (p < .0001) and naMCI (p < .0001) patients as well as controls (p < .0001). This means, that more depressive symptoms worsened subjective sleep quality. In aMCI patients we also found a significant interaction between depressive symptoms and global cognitive function (p = .002).
  
  
  CONCLUSIONS
  Depressive symptoms were the main predictor of subjective sleep quality in MCI patients and controls, but not in SCD patients. Better global cognitive function ameliorated the negative effect of depressive symptoms on the subjective sleep quality in aMCI patients.
authors.affiliation: Department of Neurology, Medical University of Vienna, Vienna, Austria.
authors.forename: Stefan
authors.initials: S
authors.lastname: Seidel
authors.affiliation: Department of Neurology, Medical University of Vienna, Vienna, Austria.
authors.forename: Peter
authors.initials: P
authors.lastname: Dal-Bianco
authors.affiliation: Department of Medical Statistics, Medical University of Vienna, Vienna, Austria.
authors.forename: Eleonore
authors.initials: E
authors.lastname: Pablik
authors.affiliation: Faculty of Psychology, University of Vienna, Vienna, Austria.
authors.forename: Nina
authors.initials: N
authors.lastname: Müller
authors.affiliation: Faculty of Psychology, University of Vienna, Vienna, Austria.
authors.forename: Claudia
authors.initials: C
authors.lastname: Schadenhofer
authors.affiliation: Faculty of Psychology, University of Vienna, Vienna, Austria.
authors.forename: Claus
authors.initials: C
authors.lastname: Lamm
authors.affiliation: Department of Neurology, Medical University of Vienna, Vienna, Austria.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Klösch
authors.affiliation: Department of Neurology, Medical University of Vienna, Vienna, Austria.
authors.forename: Doris
authors.initials: D
authors.lastname: Moser
authors.affiliation: Department of Neurology, Medical University of Vienna, Vienna, Austria.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Klug
authors.affiliation: Department of Neurology, Medical University of Vienna, Vienna, Austria.
authors.forename: Gisela
authors.initials: G
authors.lastname: Pusswald
authors.affiliation: Department of Neurology, Medical University of Vienna, Vienna, Austria.
authors.forename: Eduard
authors.initials: E
authors.lastname: Auff
authors.affiliation: Department of Neurology, Medical University of Vienna, Vienna, Austria.
authors.forename: Johann
authors.initials: J
authors.lastname: Lehrner
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D060825:Cognitive Dysfunction / Q000175:diagnosis* / Q000503:physiopathology*; D003863:Depression; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory; D008875:Middle Aged; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales; D012890:Sleep