title: Impaired Sleep Predicts Cognitive Decline in Old People: Findings from the Prospective KORA Age Study.
abstract: OBJECTIVE
  To investigate the association between sleep-related characteristics and cognitive change over 3 years of follow up in an aged population.
  
  
  METHODS
  Sleep characteristics and covariates were assessed at baseline in a standardized interview and clinical examination of the population-based KORA Age Study (n = 740, mean age = 75 years). Cognitive score (determined by telephone interview for cognitive status, TICS-m) was recorded at baseline and 3 years later.
  
  
  RESULTS
  At baseline, 82.83% (n = 613) of participants had normal cognitive status, 13.51% (n = 100) were classified with mild cognitive impairment (MCI), and 3.64% (n = 27) with probable dementia. The effect of three distinct patterns of poor sleep (difficulties initiating [DIS] or maintaining sleep [DMS], daytime sleepiness [DS] or sleep duration) were considered on a change in cognitive score with adjustments for potential confounders in generalized linear regression models. Cognitive decline was more pronounced in individuals with DMS compared to those with no DMS (β = 1.33, 95% CI = 0.41-2.24, P < 0.001). However, the predictive power of DMS was only significant in individuals with normal cognition and not impaired subjects at baseline. Prolonged sleep duration increased the risk for cognitive decline in cognitively impaired elderly (β = 1.86, 95% CI = 0.15-3.57, P = 0.03). Other sleep characteristics (DIS and DS) were not significantly associated with cognitive decline.
  
  
  CONCLUSIONS
  DMS and long sleep duration were associated with cognitive decline in normal and cognitively impaired elderly, respectively. The identification of impaired sleep quality may offer intervention strategies to deter cognitive decline in the elderly with normal cognitive function.
authors.affiliation: Institute of Epidemiology II, Helmholtz Zentrum München, German Research Centre for Environmental Health, Neuherberg, Germany.
authors.forename: Hamimatunnisa
authors.initials: H
authors.lastname: Johar
authors.affiliation: Institute of Epidemiology II, Helmholtz Zentrum München, German Research Centre for Environmental Health, Neuherberg, Germany.|Department of Medical Informatics, Biometry and Epidemiology, Ludwig- Maximilian- Universität München, Germany.|Institute of Public Health, Im Neuenheimer Feld 324, Heidelberg University, Germany.
authors.forename: Rasmila
authors.initials: R
authors.lastname: Kawan
authors.affiliation: Institute of Epidemiology II, Helmholtz Zentrum München, German Research Centre for Environmental Health, Neuherberg, Germany.
authors.forename: Rebecca Thwing
authors.initials: RT
authors.lastname: Emeny
authors.affiliation: Institute of Epidemiology II, Helmholtz Zentrum München, German Research Centre for Environmental Health, Neuherberg, Germany.|Department of Psychosomatic Medicine and Psychotherapy, Munich, Germany.
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Ladwig
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D003071:Cognition; D060825:Cognitive Dysfunction / Q000453:epidemiology* / Q000523:psychology; D003704:Dementia / Q000453:epidemiology / Q000523:psychology; D005260:Female; D005858:Germany / Q000453:epidemiology; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012890:Sleep; D007319:Sleep Initiation and Maintenance Disorders / Q000453:epidemiology / Q000503:physiopathology* / Q000523:psychology*; D012894:Sleep Stages; D013997:Time Factors
keywords: cognitive decline; dementia; elderly; sleep