title: Daytime somnolence as an early sign of cognitive decline in a community-based study of older people.
abstract: OBJECTIVE
  This study aimed to examine the association between self-reported sleep problems and cognitive decline in community-dwelling older people. We hypothesized that daytime somnolence predicts subsequent cognitive decline.
  
  
  METHODS
  This is a longitudinal study in a 3.2-year follow-up, with 18-month intervals. The setting is the Washington Heights-Inwood Community Aging Project. There were 1098 participants, who were over 65 years old and recruited from the community. Sleep problems were estimated using five sleep categories derived from the RAND Medical Outcome Study Sleep Scale: sleep disturbance, snoring, awaken short of breath/with a headache, sleep adequacy, and daytime somnolence. Four distinct cognitive composite scores were calculated: memory, language, speed of processing, and executive functioning. We used generalized estimating equations analyses with cognitive scores as the outcome, and time, sleep categories and their interactions as the main predictors. Models were initially unadjusted and then adjusted for age, gender, education, ethnicity, depression, and apolipoprotein E-ε4 genotype.
  
  
  RESULTS
  Increased daytime somnolence (including feeling drowsy/sleepy, having trouble staying awake, and taking naps during the day) was linked to slower speed of processing both cross-sectionally (B = -0.143, p = 0.047) and longitudinally (B = -0.003, p = 0.027). After excluding the demented participants at baseline, the results remained significant (B = -0.003, p = 0.021).
  
  
  CONCLUSIONS
  Our findings suggest that daytime somnolence may be an early sign of cognitive decline in the older population.
authors.affiliation: Cognitive Neuroscience Division, Department of Neurology and The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University College of Physicians and Surgeons, New York, NY, USA.
authors.forename: Angeliki
authors.initials: A
authors.lastname: Tsapanou
authors.affiliation: Cognitive Neuroscience Division, Department of Neurology and The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University College of Physicians and Surgeons, New York, NY, USA.
authors.forename: Yian
authors.initials: Y
authors.lastname: Gu
authors.affiliation: Cognitive Neuroscience Division, Department of Neurology and The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University College of Physicians and Surgeons, New York, NY, USA.
authors.forename: Deirdre
authors.initials: D
authors.lastname: O'Shea
authors.affiliation: Cognitive Neuroscience Division, Department of Neurology and The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University College of Physicians and Surgeons, New York, NY, USA.
authors.forename: Teal
authors.initials: T
authors.lastname: Eich
authors.affiliation: The Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA.|Department of Biostatistics, Joseph P. Mailman School of Public Health, Columbia University, New York, NY, USA.
authors.forename: Ming-Xin
authors.initials: MX
authors.lastname: Tang
authors.affiliation: Cognitive Neuroscience Division, Department of Neurology and The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University College of Physicians and Surgeons, New York, NY, USA.|The Gertrude H. Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, NY, USA.|The Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA.|The Division of Epidemiology, Joseph P. Mailman School of Public Health, Columbia University, New York, NY, USA.
authors.forename: Nicole
authors.initials: N
authors.lastname: Schupf
authors.affiliation: Cognitive Neuroscience Division, Department of Neurology and The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University College of Physicians and Surgeons, New York, NY, USA.|The Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA.|The Division of Epidemiology, Joseph P. Mailman School of Public Health, Columbia University, New York, NY, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Manly
authors.affiliation: Department of Psychology, Fordham University, Bronx, NY, USA.
authors.forename: Molly
authors.initials: M
authors.lastname: Zimmerman
authors.affiliation: Cognitive Neuroscience Division, Department of Neurology and The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University College of Physicians and Surgeons, New York, NY, USA.|The Gertrude H. Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, NY, USA.|The Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA.|The Division of Epidemiology, Joseph P. Mailman School of Public Health, Columbia University, New York, NY, USA.|National and Kapodistrian University of Athens Medical School, Athens, Greece.
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Scarmeas
authors.affiliation: Cognitive Neuroscience Division, Department of Neurology and The Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University College of Physicians and Surgeons, New York, NY, USA.|The Gertrude H. Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, NY, USA.|The Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY, USA.|The Division of Epidemiology, Joseph P. Mailman School of Public Health, Columbia University, New York, NY, USA.
authors.forename: Yaakov
authors.initials: Y
authors.lastname: Stern
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003071:Cognition / Q000502:physiology; D003072:Cognition Disorders / Q000150:complications* / Q000503:physiopathology; D003430:Cross-Sectional Studies; D056344:Executive Function / Q000502:physiology; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008568:Memory / Q000502:physiology; D009483:Neuropsychological Tests; D012893:Sleep Wake Disorders / Q000209:etiology* / Q000503:physiopathology
keywords: cognitive decline; daytime somnolence; older; speed of processing