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Original Investigation
October 2017

Association of Sleep-Disordered Breathing With Cognitive Function and Risk of Cognitive Impairment: A Systematic Review and Meta-analysis

Author Affiliations
  • 1Department of Psychiatry, University of California, San Francisco
  • 2School of Medicine, Dentistry, and Biomedical Sciences, Queen’s University, Belfast, United Kingdom
  • 3Department of Epidemiology and Biostatistics, University of California, San Francisco
  • 4Department of Psychiatry, University of California, San Francisco
  • 5Department of Neurology, University of California, San Francisco
  • 6Department of Epidemiology, University of California, San Francisco
  • 7San Francisco VA Medical Center, San Francisco, California
JAMA Neurol. 2017;74(10):1237-1245. doi:10.1001/jamaneurol.2017.2180
Key Points

Question  What are the effects of sleep-disordered breathing (SDB) on cognitive function and risk of cognitive impairment?

Findings  In this systematic review meta-analysis that included more than 4 million participants, those with SDB were 26% more likely to develop cognitive impairment than those without SDB. They also had slightly worse performance in executive function but not in global cognition or memory.

Meaning  Sleep-disordered breathing may be an important modifiable risk factor for dementia and other cognitive impairment; future studies are needed to examine if treatment of SDB might reduce risk of cognitive impairment.

Abstract

Importance  Growing evidence suggests an association between sleep-disordered breathing (SDB) and cognitive decline in elderly persons. However, results from population-based studies have been conflicting, possibly owing to different methods to assess SDB or cognitive domains, making it difficult to draw conclusions on this association.

Objective  To provide a quantitative synthesis of population-based studies on the relationship between SDB and risk of cognitive impairment.

Data Sources  PubMed, EMBASE, and PsychINFO were systematically searched to identify peer-reviewed articles published in English before January 2017 that reported on the association between SDB and cognitive function.

Study Selection  We included cross-sectional and prospective studies with at least 200 participants with a mean participant age of 40 years or older.

Data Extraction and Synthesis  Data were extracted independently by 2 investigators. We extracted and pooled adjusted risk ratios from prospective studies and standard mean differences from cross-sectional studies, using random-effect models. This meta-analysis followed the PRISMA guidelines and also adhered to the MOOSE guidelines.

Main Outcomes and Measures  Cognitive outcomes were based on standard tests or diagnosis of cognitive impairment. Sleep-disordered breathing was ascertained by apnea-hypopnea index or clinical diagnosis.

Results  We included 14 studies, 6 of which were prospective, covering a total of 4 288 419 men and women. Pooled analysis of the 6 prospective studies indicated that those with SDB were 26% (risk ratio, 1.26; 95% CI, 1.05-1.50) more likely to develop cognitive impairment, with no evidence of publication bias but significant heterogeneity between studies. After removing 1 study that introduced significant heterogeneity, the pooled risk ratio was 1.35 (95% CI, 1.11-1.65). Pooled analysis of the 7 cross-sectional studies suggested that those with SDB had slightly worse executive function (standard mean difference, −0.05; 95% CI, −0.09 to 0.00), with no evidence of heterogeneity or publication bias. Sleep-disordered breathing was not associated with global cognition or memory.

Conclusions and Relevance  Sleep-disordered breathing is associated with an increased risk of cognitive impairment and a small worsening in executive function. Further studies are required to determine the mechanisms linking these common conditions and whether treatment of SDB might reduce risk of cognitive impairment.

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