Neuropsychological Effects of One-Week Continuous Positive Airway Pressure Treatment in Patients With Obstructive Sleep Apnea: A Placebo-Controlled Study

Objective To determine whether 1-week continuous positive airway pressure (CPAP) treatment, compared with placebo CPAP, improves cognitive functioning in patients with obstructive sleep apnea (OSA). Methods 36 OSA patients (aged 32–60 years, respiratory disturbance index [RDI]> 15) were monitored 2 nights with polysomnography, then randomized for 1-week treatment to CPAP or placebo (CPAP at 2 cm H2O with holes in mask). Participants completed Wechsler Adult Intelligence Scale—Revised Digit Symbol and Digit Span, Trailmaking A/B, Digit Vigilance, Stroop Color-Word, Digit Ordering, and Word Fluency tests pre- and posttreatment. These produced 22 scores per participant, which were analyzed by use of repeated-measures analysis of variance (ANOVA) and a rank-sum test. Results In ANOVA, only 1 of the 22 scores showed significant changes specific to CPAP treatment, a number that could be expected by chance alone: Digit Vigilance-Time (p = .035). The CPAP group improved their time (from 7.5 to 6.9 minutes, p = .013). The rank-sum test revealed that the CPAP group had significantly better overall cognitive functioning posttreatment than the placebo group (mean ranks of 17.8 vs. 20.2, respectively;p = .022). Conclusions Although results suggest overall cognitive improvement due to CPAP, no beneficial effects in any specific cognitive domain were found. Future studies of neuropsychological effects of CPAP treatment should include a placebo CPAP control group. Placebo studies that use longer-term treatment might demonstrate additional effects. It is also possible that, even at 2 cm H2O, CPAP conveys some beneficial neuropsychological effects.