Neuropsychological effects of one-week continuous positive airway pressuretreatment 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 functionin g 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 CPA P or placebo (CPAP at 2 cm H2O with holes in mask). Participants completed Wechsler Adult Intelligence Scale-Revised Digit Symbol and Digit Span, Trai lmaking A/B, Digit Vigilance, Stroop Color-Word, Digit Ordering, and Word F luency tests pre- and posttreatment. These produced 22 scores per participa nt, which were analyzed by use of repeated-measures analysis of variance (A NOVA) and a rank-sum test. Results: In ANOVA, only I of the 22 scores showe d significant changes specific to CPAP treatment, a number that could be ex pected by chance alone: Digit Vigilance-Time (p = .035). The CPAP group imp roved their time (from 7.5 to 6.9 minutes, p = .013). The rank-sum test rev ealed that the CPAP group had significantly better overall cognitive functi oning posttreatment than the placebo group (mean ranks of 17.8 vs. 20.2. re spectively: p = .022). Conclusions: Although results suggest overall cognit ive improvement due to CPAP, no beneficial effects in any specific cognitiv e domain were found, Future studies of neuropsychological effects of CPAP t reatment 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 neuropsycholo gical effects.