title: Sleep-disordered breathing, hypoxia, and risk of mild cognitive impairment and dementia in older women.
abstract: BACKGROUND
  Sleep-disordered breathing (characterized by recurrent arousals from sleep and intermittent hypoxemia) is common among older adults. Cross-sectional studies have linked sleep-disordered breathing to poor cognition; however, it remains unclear whether sleep-disordered breathing precedes cognitive impairment in older adults.
  
  
  OBJECTIVE
  To determine the prospective relationship between sleep-disordered breathing and cognitive impairment and to investigate potential mechanisms of this association.
  
  
  METHODS
  Prospective sleep and cognition study of 298 women without dementia (mean [SD] age: 82.3 [3.2] years) who had overnight polysomnography measured between January 2002 and April 2004 in a substudy of the Study of Osteoporotic Fractures. Sleep-disordered breathing was defined as an apnea-hypopnea index of 15 or more events per hour of sleep. Multivariate logistic regression was used to determine the independent association of sleep-disordered breathing with risk of mild cognitive impairment or dementia, adjusting for age, race, body mass index, education level, smoking status, presence of diabetes, presence of hypertension, medication use (antidepressants, benzodiazepines, or nonbenzodiazepine anxiolytics), and baseline cognitive scores. Measures of hypoxia, sleep fragmentation, and sleep duration were investigated as underlying mechanisms for this relationship.
  
  
  METHODS
  Adjudicated cognitive status (normal, dementia, or mild cognitive impairment) based on data collected between November 2006 and September 2008.
  
  
  RESULTS
  Compared with the 193 women without sleep-disordered breathing, the 105 women (35.2%) with sleep-disordered breathing were more likely to develop mild cognitive impairment or dementia (31.1% [n = 60] vs 44.8% [n = 47]; adjusted odds ratio [AOR], 1.85; 95% confidence interval [CI], 1.11-3.08). Elevated oxygen desaturation index (≥15 events/hour) and high percentage of sleep time (>7%) in apnea or hypopnea (both measures of disordered breathing) were associated with risk of developing mild cognitive impairment or dementia (AOR, 1.71 [95% CI, 1.04-2.83] and AOR, 2.04 [95% CI, 1.10-3.78], respectively). Measures of sleep fragmentation (arousal index and wake after sleep onset) or sleep duration (total sleep time) were not associated with risk of cognitive impairment.
  
  
  CONCLUSIONS
  Among older women, those with sleep-disordered breathing compared with those without sleep-disordered breathing had an increased risk of developing cognitive impairment.
authors.affiliation: Department of Psychiatry, University of California, San Francisco, San Francisco, CA 94121, USA. kristine.yaffe@ucsf.edu
authors.forename: Kristine
authors.initials: K
authors.lastname: Yaffe
authors.forename: Alison M
authors.initials: AM
authors.lastname: Laffan
authors.forename: Stephanie Litwack
authors.initials: SL
authors.lastname: Harrison
authors.forename: Susan
authors.initials: S
authors.lastname: Redline
authors.forename: Adam P
authors.initials: AP
authors.lastname: Spira
authors.forename: Kristine E
authors.initials: KE
authors.lastname: Ensrud
authors.forename: Sonia
authors.initials: S
authors.lastname: Ancoli-Israel
authors.forename: Katie L
authors.initials: KL
authors.lastname: Stone
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D003072:Cognition Disorders / Q000150:complications*; D045422:Continuous Positive Airway Pressure; D003704:Dementia / Q000150:complications*; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000150:complications / Q000209:etiology; D017286:Polysomnography; D011446:Prospective Studies; D012306:Risk; D012891:Sleep Apnea Syndromes / Q000150:complications* / Q000628:therapy