title: Abnormal daytime sleepiness in dementia with Lewy bodies compared to Alzheimer's disease using the Multiple Sleep Latency Test.
abstract: BACKGROUND
  Excessive daytime sleepiness is a commonly reported problem in dementia with Lewy bodies (DLB). We examined the relationship between nighttime sleep continuity and the propensity to fall asleep during the day in clinically probable DLB compared to Alzheimer's disease (AD) dementia.
  
  
  METHODS
  A full-night polysomnography was carried out in 61 participants with DLB and 26 with AD dementia. Among this group, 32 participants with DLB and 18 with AD dementia underwent a daytime Multiple Sleep Latency Test (MSLT). Neuropathologic examinations of 20 participants with DLB were carried out.
  
  
  RESULTS
  Although nighttime sleep efficiency did not differentiate diagnostic groups, the mean MSLT initial sleep latency was significantly shorter in participants with DLB than in those with AD dementia (mean 6.4 ± 5 minutes vs 11 ± 5 minutes, P <0.01). In the DLB group, 81% fell asleep within 10 minutes compared to 39% of the AD dementia group (P <0.01), and 56% in the DLB group fell asleep within 5 minutes compared to 17% in the AD dementia group (P <0.01). Daytime sleepiness in AD dementia was associated with greater dementia severity, but mean MSLT latency in DLB was not related to dementia severity, sleep efficiency the night before, or to visual hallucinations, fluctuations, parkinsonism or rapid eye movement sleep behavior disorder. These data suggest that abnormal daytime sleepiness is a unique feature of DLB that does not depend on nighttime sleep fragmentation or the presence of the four cardinal DLB features. Of the 20 DLB participants who underwent autopsy, those with transitional Lewy body disease (brainstem and limbic) did not differ from those with added cortical pathology (diffuse Lewy body disease) in dementia severity, DLB core features or sleep variables.
  
  
  CONCLUSIONS
  Daytime sleepiness is more likely to occur in persons with DLB than in those with AD dementia. Daytime sleepiness in DLB may be attributed to disrupted brainstem and limbic sleep-wake physiology, and further work is needed to better understand the underlying mechanisms.
authors.affiliation: Department of Psychiatry and Psychology, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224 USA.
authors.forename: Tanis J
authors.initials: TJ
authors.lastname: Ferman
authors.affiliation: Department of Psychiatry and Psychology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905 USA.
authors.forename: Glenn E
authors.initials: GE
authors.lastname: Smith
authors.affiliation: Department of Pathology, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224 USA.
authors.forename: Dennis W
authors.initials: DW
authors.lastname: Dickson
authors.affiliation: Department of Neurology, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224 USA.
authors.forename: Neill R
authors.initials: NR
authors.lastname: Graff-Radford
authors.affiliation: Center for Sleep Medicine, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224 USA.
authors.forename: Siong-Chi
authors.initials: SC
authors.lastname: Lin
authors.affiliation: Department of Neurology, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224 USA.
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Wszolek
authors.affiliation: Department of Neurology, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224 USA.
authors.forename: Jay A
authors.initials: JA
authors.lastname: Van Gerpen
authors.affiliation: Department of Neurology, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL 32224 USA.
authors.forename: Ryan
authors.initials: R
authors.lastname: Uitti
authors.affiliation: Department of Neurology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905 USA.
authors.forename: David S
authors.initials: DS
authors.lastname: Knopman
authors.affiliation: Department of Neurology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905 USA.
authors.forename: Ronald C
authors.initials: RC
authors.lastname: Petersen
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905 USA.
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Parisi
authors.affiliation: Center for Sleep Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905 USA.
authors.forename: Michael H
authors.initials: MH
authors.lastname: Silber
authors.affiliation: Department of Neurology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905 USA ; Center for Sleep Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905 USA.
authors.forename: Bradley F
authors.initials: BF
authors.lastname: Boeve