title: A distinctive interaction between memory and chronic daytime somnolence in asymptomatic APOE e4 homozygotes.
abstract: OBJECTIVE
  To correlate memory measures with a trait measure of chronic daytime somnolence in cognitively normal individuals with different gene doses of the apolipoprotein E (APOE) e4 allele, a common Alzheimer's disease susceptibility gene.
  
  
  METHODS
  Cross-sectional, exploratory study of cognitive abilities in APOE e4 homozygotes (HMZ) (n=42), heterozygotes (HTZ), (n=42) and noncarriers (NC) (n=42) who are matched for age, gender, educational level, and family history of dementia.
  
  
  METHODS
  Tertiary care academic medical center.
  
  
  METHODS
  Cognitively normal residents of Maricopa County, Arizona who are 30-70 years of age, genotyped for APOE, and have no history of a sleep disorder
  
  
  METHODS
  N/A.
  
  
  METHODS
  Epworth Sleepiness Scale (ESS) and a battery of neuropsychological tests
  
  
  RESULTS
  Age, education, gender, and insomnia complaints did not significantly differ among groups. Despite normal baseline memory scores, memory declined with increasing ESS on all eight memory measures in the HMZ, two of eight in the HTZ, and one of eight in the NC. Differences between HMZ and NC on the slope of memory decline with increasing ESS reached statistical significance on two verbal memory measures, AVLT Long-Term Memory (p=0.048) and Percent Delayed Recall (p=0.035).
  
  
  CONCLUSIONS
  Chronic daytime somnolence is associated with a distinctive decline in verbal memory in cognitively normal APOE e4 HMZ, a group at particularly high risk of Alzheimer's disease. Additional studies are needed to confirm these exploratory findings and to determine the effects of acute somnolence on cognition in these genetic subgroups.
authors.affiliation: Department of Neurology, Mayo Clinic Scottsdale, University of Arizona, 85259, USA. Caselli.Richard@Mayo.edu
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Caselli
authors.forename: Eric M
authors.initials: EM
authors.lastname: Reiman
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Hentz
authors.forename: David
authors.initials: D
authors.lastname: Osborne
authors.forename: Gene E
authors.initials: GE
authors.lastname: Alexander
authors.forename: Bradley F
authors.initials: BF
authors.lastname: Boeve
mesh_terms: D000328:Adult; D000368:Aged; D000483:Alleles; D000544:Alzheimer Disease / Q000235:genetics* / Q000378:metabolism; D001057:Apolipoproteins E / Q000235:genetics* / Q000378:metabolism; D002908:Chronic Disease; D003430:Cross-Sectional Studies; D006970:Disorders of Excessive Somnolence / Q000150:complications*; D005838:Genotype; D006720:Homozygote; D006801:Humans; D008569:Memory Disorders / Q000175:diagnosis / Q000209:etiology*; D008875:Middle Aged; D009483:Neuropsychological Tests
chemical_list: D001057:Apolipoproteins E