title: Memory before and after sleep in patients with moderate obstructive sleep apnea.
abstract: OBJECTIVE
  The aim of this study was to investigate the effects of obstructive sleep apnea (OSA) on procedural and declarative memory encoding in the evening prior to sleep, on memory consolidation during subsequent sleep, and on retrieval in the morning after sleep.
  
  
  METHODS
  Memory performance (procedural mirror-tracing task, declarative visual and verbal memory task) and general neuropsychological performance were assessed before and after one night of polysomnographic monitoring in 15 patients with moderate OSA and 20 age-, sex-, and IQ-matched healthy subjects.
  
  
  RESULTS
  Encoding levels prior to sleep were similar across groups for all tasks. Conventional analyses of averaged mirror tracing performance suggested a significantly reduced overnight improvement in OSA patients. Single trial analyses, however, revealed that this effect was due to significantly flattened learning curves in the evening and morning session in OSA patients. OSA patients showed a significantly lower verbal retention rate and a non-significantly reduced visual retention rate after sleep compared to healthy subjects. Polysomnography revealed a significantly reduced REM density, increased frequency of micro-arousals, elevated apnea-hypopnea index, and subjectively disturbed sleep quality in OSA patients compared to healthy subjects.
  
  
  CONCLUSIONS
  The results suggest that moderate OSA is associated with a significant impairment of procedural and verbal declarative memory. Future work is needed to further determine the contribution of structural or functional alterations in brain circuits relevant for memory, and to test whether OSA treatment improves or normalizes the observed deficits in learning.
authors.affiliation: Department of Psychiatry and Psychotherapy, University Medical Center Freiburg, Germany. corinna.kloepfer@uniklinik-freiburg.de
authors.forename: Corinna
authors.initials: C
authors.lastname: Kloepfer
authors.forename: Dieter
authors.initials: D
authors.lastname: Riemann
authors.forename: Eric A
authors.initials: EA
authors.lastname: Nofzinger
authors.forename: Bernd
authors.initials: B
authors.lastname: Feige
authors.forename: Josef
authors.initials: J
authors.lastname: Unterrainer
authors.forename: Ruth
authors.initials: R
authors.lastname: O'Hara
authors.forename: Stephan
authors.initials: S
authors.lastname: Sorichter
authors.forename: Christoph
authors.initials: C
authors.lastname: Nissen
mesh_terms: D000704:Analysis of Variance; D015984:Causality; D015897:Comorbidity; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000453:epidemiology*; D008570:Memory, Short-Term; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D017286:Polysomnography / Q000379:methods / Q000706:statistics & numerical data; D012720:Severity of Illness Index; D012890:Sleep; D020181:Sleep Apnea, Obstructive / Q000453:epidemiology*; D012894:Sleep Stages; D011795:Surveys and Questionnaires; D014706:Verbal Learning
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