title: Hypoxemia correlates with attentional dysfunction in patients with obstructive sleep apnea.
abstract: OBJECTIVE
  Obstructive sleep apnea is associated with cognitive impairment, but whether hypoxemia or repeated arousals and sleepiness are the underlying mechanism is controversial. Studies using a wide range of attention and executive functions tests in patients with severe sleep apnea are lacking.
  
  
  METHODS
  In a prospective cohort study, 40 patients aged 30-70 years, diagnosed with obstructive sleep apnea (apnea-hypopnea index ≥5) were recruited. Patients with known cardiovascular, pulmonary, psychiatric, or neurological disease, and or patients receiving anti-psychotic, sedatives, or stimulant medications were excluded. Patients underwent full overnight polysomnography including continuous oxygen saturation measurements followed by extensive neuropsychological testings in attention and executive function domains. The correlation between sleep apnea severity and patients' performance on the neuropsychological tests was examined.
  
  
  RESULTS
  The patients' performance on measures of attention and executive function was significantly worse compared to the average in a normal population. Attention, as reflected by the number of omissions and by the reaction time on the Conners' Continuous Performance Test correlated significantly with the apnea-hypopnea index (r = 0.6, p < 0.001 and r = 0.48, p = 0.003, respectively) and with parameters of hypoxemia, namely the average SpO(2) (r = -0.51, p = 0.002 and r = -0.39, p = 0.02, respectively) and the percent time spent with SpO(2) < 90% (r = 0.57, p < 0.001 and r = 0.39, p = 0.02, respectively), but not with the degree of sleepiness. Executive dysfunction did not correlate with sleep parameters.
  
  
  CONCLUSIONS
  Attention is the predominant cognitive function affected in patients with obstructive sleep apnea and correlates primarily with nocturnal hypoxemia rather than daytime sleepiness or sleep fragmentation. Executive functions, while below average in some patients, do not correlate with polysomnographic parameters.
authors: The Institute of Pulmonary Medicine, Assaf Harofeh Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Zerifin, Israel.
authors: Isaac
authors: I
authors: Shpirer
authors: Arnon
authors: A
authors: Elizur
authors: Ran
authors: R
authors: Shorer
authors: Ruth Bernstein
authors: RB
authors: Peretz
authors: Jose M
authors: JM
authors: Rabey
authors: Michael
authors: M
authors: Khaigrekht
mesh_terms: D000328:Adult; D000368:Aged; D001143:Arousal / Q000502:physiology; D001288:Attention; D001289:Attention Deficit Disorder with Hyperactivity / Q000097:blood* / Q000453:epidemiology / Q000523:psychology*; D015331:Cohort Studies; D006970:Disorders of Excessive Somnolence / Q000097:blood / Q000453:epidemiology / Q000523:psychology; D056344:Executive Function; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000097:blood* / Q000453:epidemiology / Q000523:psychology*; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D017286:Polysomnography; D011446:Prospective Studies; D011594:Psychometrics; D011930:Reaction Time; D020181:Sleep Apnea, Obstructive / Q000097:blood* / Q000453:epidemiology / Q000523:psychology*; D013223:Statistics as Topic