title: Prolonged sleep duration as a marker of early neurodegeneration predicting incident dementia.
abstract: OBJECTIVE
  To evaluate the association between sleep duration and the risk of incident dementia and brain aging.
  
  
  METHODS
  Self-reported total hours of sleep were examined in the Framingham Heart Study (n = 2,457, mean age 72 ± 6 years, 57% women) as a 3-level variable: <6 hours (short), 6-9 hours (reference), and >9 hours (long), and was related to the risk of incident dementia over 10 years, and cross-sectionally to total cerebral brain volume (TCBV) and cognitive performance.
  
  
  RESULTS
  We observed 234 cases of all-cause dementia over 10 years of follow-up. In multivariable analyses, prolonged sleep duration was associated with an increased risk of incident dementia (hazard ratio [HR] 2.01; 95% confidence interval [CI] 1.24-3.26). These findings were driven by persons with baseline mild cognitive impairment (HR 2.83; 95% CI 1.06-7.55) and persons without a high school degree (HR 6.05; 95% CI 3.00-12.18). Transitioning to sleeping >9 hours over a mean period of 13 years before baseline was associated with an increased risk of all-cause dementia (HR 2.43; 95% CI 1.44-4.11) and clinical Alzheimer disease (HR 2.20; 95% CI 1.17-4.13). Relative to sleeping 6-9 hours, long sleep duration was also associated cross-sectionally with smaller TCBV (β ± SE, -1.08 ± 0.41 mean units of TCBV difference) and poorer executive function (β ± SE, -0.41 ± 0.13 SD units of Trail Making Test B minus A score difference).
  
  
  CONCLUSIONS
  Prolonged sleep duration may be a marker of early neurodegeneration and hence a useful clinical tool to identify those at a higher risk of progressing to clinical dementia within 10 years.
authors.affiliation: From the Department of Neurology (A.J.W., A.B., J.J.H., S.H.A., M.P.P., S.S.), Boston University School of Medicine; Department of Biostatistics (A.B., J.J.H.), Boston University School of Public Health; Framingham Heart Study (A.B., J.J.H., S.H.A., M.P.P., S.S.); Department of Neuroscience (N.J.), Boston University, MA; University of California at Davis (C.D.), Sacramento; and Center for Human Psychopharmacology (M.P.P.), Swinburne University of Technology, Australia.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Westwood
authors.affiliation: From the Department of Neurology (A.J.W., A.B., J.J.H., S.H.A., M.P.P., S.S.), Boston University School of Medicine; Department of Biostatistics (A.B., J.J.H.), Boston University School of Public Health; Framingham Heart Study (A.B., J.J.H., S.H.A., M.P.P., S.S.); Department of Neuroscience (N.J.), Boston University, MA; University of California at Davis (C.D.), Sacramento; and Center for Human Psychopharmacology (M.P.P.), Swinburne University of Technology, Australia.
authors.forename: Alexa
authors.initials: A
authors.lastname: Beiser
authors.affiliation: From the Department of Neurology (A.J.W., A.B., J.J.H., S.H.A., M.P.P., S.S.), Boston University School of Medicine; Department of Biostatistics (A.B., J.J.H.), Boston University School of Public Health; Framingham Heart Study (A.B., J.J.H., S.H.A., M.P.P., S.S.); Department of Neuroscience (N.J.), Boston University, MA; University of California at Davis (C.D.), Sacramento; and Center for Human Psychopharmacology (M.P.P.), Swinburne University of Technology, Australia.
authors.forename: Nikita
authors.initials: N
authors.lastname: Jain
authors.affiliation: From the Department of Neurology (A.J.W., A.B., J.J.H., S.H.A., M.P.P., S.S.), Boston University School of Medicine; Department of Biostatistics (A.B., J.J.H.), Boston University School of Public Health; Framingham Heart Study (A.B., J.J.H., S.H.A., M.P.P., S.S.); Department of Neuroscience (N.J.), Boston University, MA; University of California at Davis (C.D.), Sacramento; and Center for Human Psychopharmacology (M.P.P.), Swinburne University of Technology, Australia.
authors.forename: Jayandra J
authors.initials: JJ
authors.lastname: Himali
authors.affiliation: From the Department of Neurology (A.J.W., A.B., J.J.H., S.H.A., M.P.P., S.S.), Boston University School of Medicine; Department of Biostatistics (A.B., J.J.H.), Boston University School of Public Health; Framingham Heart Study (A.B., J.J.H., S.H.A., M.P.P., S.S.); Department of Neuroscience (N.J.), Boston University, MA; University of California at Davis (C.D.), Sacramento; and Center for Human Psychopharmacology (M.P.P.), Swinburne University of Technology, Australia.
authors.forename: Charles
authors.initials: C
authors.lastname: DeCarli
authors.affiliation: From the Department of Neurology (A.J.W., A.B., J.J.H., S.H.A., M.P.P., S.S.), Boston University School of Medicine; Department of Biostatistics (A.B., J.J.H.), Boston University School of Public Health; Framingham Heart Study (A.B., J.J.H., S.H.A., M.P.P., S.S.); Department of Neuroscience (N.J.), Boston University, MA; University of California at Davis (C.D.), Sacramento; and Center for Human Psychopharmacology (M.P.P.), Swinburne University of Technology, Australia.
authors.forename: Sanford H
authors.initials: SH
authors.lastname: Auerbach
authors.affiliation: From the Department of Neurology (A.J.W., A.B., J.J.H., S.H.A., M.P.P., S.S.), Boston University School of Medicine; Department of Biostatistics (A.B., J.J.H.), Boston University School of Public Health; Framingham Heart Study (A.B., J.J.H., S.H.A., M.P.P., S.S.); Department of Neuroscience (N.J.), Boston University, MA; University of California at Davis (C.D.), Sacramento; and Center for Human Psychopharmacology (M.P.P.), Swinburne University of Technology, Australia. matthewpase@gmail.com suseshad@bu.edu.
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Pase
authors.affiliation: From the Department of Neurology (A.J.W., A.B., J.J.H., S.H.A., M.P.P., S.S.), Boston University School of Medicine; Department of Biostatistics (A.B., J.J.H.), Boston University School of Public Health; Framingham Heart Study (A.B., J.J.H., S.H.A., M.P.P., S.S.); Department of Neuroscience (N.J.), Boston University, MA; University of California at Davis (C.D.), Sacramento; and Center for Human Psychopharmacology (M.P.P.), Swinburne University of Technology, Australia. matthewpase@gmail.com suseshad@bu.edu.
authors.forename: Sudha
authors.initials: S
authors.lastname: Seshadri
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001057:Apolipoproteins E / Q000235:genetics; D002540:Cerebral Cortex / Q000000981:diagnostic imaging; D015331:Cohort Studies; D003704:Dementia / Q000175:diagnosis* / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D019636:Neurodegenerative Diseases / Q000150:complications*; D009483:Neuropsychological Tests; D012111:Residence Characteristics; D057566:Self Report; D012893:Sleep Wake Disorders / Q000453:epidemiology* / Q000209:etiology*
chemical_list: D001057:Apolipoproteins E