Purpose: Obstructive sleep apnea syndrome (OSAS) is associated with impaired cognition, especially executive functions. However, various of its comorbid conditions are also known to cause cognitive impairment, so it is unclear whether OSAS itself is responsible for cognitive deficits. Our aim was to determine the effects of OSAS on executive functions in otherwise healthy patients.
Method: This was a parallel group design study, which involved 22 patients aged 36-65 years diagnosed with moderate to severe OSAS, whose body mass index was below 26, and who did not have diabetes, hypertension, or depression. Controls were 22 healthy individuals with similar age, gender, intelligence quotient, and schooling to those of the patients. Participants completed a test battery that included measures of 6 distinct executive domains (shifting, inhibition, updating, dual-task performance, planning, and access to long-term memory), of all subsystems of the multiple-component working memory model, attention, and mood.
Results: OSAS and controls were equivalent in all demographic variables and test scores. The apnea-hypopnea index did not significantly correlate with executive performance, but mean oxygen saturation did so with measurements of executive shifting and access to long-term memory.
Conclusions: OSAS without comorbidities did not lead to cognitive impairment.