Obstructive sleep apnea–hypopnea and neurocognitive functioning in the Sleep Heart Health Study
Received 19 October 2005; received in revised form 8 February 2006; accepted 12 February 2006.
Abstract
Background and purpose
Obstructive sleep apnea–hypopnea (OSAH) is associated with sleep fragmentation and nocturnal hypoxemia. In clinical samples, patients with OSAH frequently are found to have deficits in neuropsychological function. However, the nature and severity of these abnormalities in non-clinical populations is less well defined.
Patients and methods
One hundred and forty-one participants from the Tucson, AZ and New York, NY field centers of the Sleep Heart Health Study completed a battery of neuropsychological tests for 9–40 months (mean=24 months, SD=7 months) after an unattended home polysomnogram. Sixty-seven participants had OSAH (AHI>10) and 74 did not have OSAH (control (CTL), apnea–hypopnea index (AHI)<5). In addition to the individual tests, composite variables representing attention, executive function, MotorSpeed and processing speed were constructed from the neuropsychological test battery.
Results
There were no significant differences in any individual neuropsychological test or composite variable between the OSAH and CTL groups. However, when time spent with O2 saturations less than 85% was dichotomized into those participants in the top quartile of the distribution and those in the lower three quartiles, motor speed was significantly impaired in those who were more hypoxemic. In addition, poorer motor speed (model adjusted R2=0.242, P<0.001) and processing speed performance (model adjusted R2=0.122, P<0.001) were associated with more severe oxygen desaturation even after controlling for degree of daytime sleepiness, age, gender and educational level.
Conclusions
Mild to moderate OSAH has little impact on the selected measures of attention, executive function, motor speed and processing speed. However, hypoxemia adversely affects both motor and processing speed. These results suggest that in middle-aged to elderly adults the neuropsychological effects of clinically unrecognized mild to moderate OSAH are neither global nor large.
aDepartment of Medicine, Arizona Respiratory, Sleep Disorders and General Clinical Research Centers, University of Arizona College of Medicine, 1501 North Campbell, Room 2305 Tucson, AZ 85724, USA
bDepartment of Psychiatry and General Clinical Research Center, University of Arizona College of Medicine, Tucson, AZ, USA
cCollege of Nursing (Southwest Borderlands), Arizona State University, Tempe, AZ, USA
dDepartment of Pediatrics, Steele Memorial Children's Research and General Clinical Research Centers, University of Arizona College of Medicine, Tucson, AZ, USA
eDepartment of Medicine and Arizona Respiratory Center, University of Arizona College of Medicine, Tucson, AZ, USA
fDepartment of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA
gDepartment of Psychology, University of Arizona, Tucson, AZ, USA
hDivision of Epidemiology, School of Public Health, University of Minnesota, Minneapolis, MN, USA
iDepartment of Neurology, Columbia University, New York, NY, USA
jDepartments of Psychology and Psychiatry, Sleep Disorders Center, University of Arizona, Tucson, AZ, USA
ABSTRACT