Continuous positive airway pressure treatment impact on memory processes in obstructive sleep apnea patients: a randomized sham-controlled trial

Objective: The aim of this study was to investigate the changes in a large panel of memory processes after six weeks of continuous positive airway pressure (CPAP) in obstructive sleep apnea (OSA) patients. This randomized controlled trial compared the influence of effective CPAP to sham CPAP over six weeks on different memory processes in OSA patients. Methods: The study took place in a sleep laboratory and outpatient sleep clinic in a French tertiary-care university hospital. A total of 36 patients with OSA were randomized to receive either CPAP (n = 18) or sham CPAP (n = 18) for six weeks. Interventions were either effective CPAP or non-effective sham CPAP, for six weeks. All patients underwent an extensive battery of tasks evaluating three separate memory systems, before and after treatment. Verbal episodic memory was tested after forced encoding, procedural memory was tested using simplified versions of mirror drawing and reading tests, and working memory was examined with validated paradigms based on a theoretical model. Results: The study subjects were 55 +/- 11 years of age and 72.2% were male. The mean body mass index was 29.5 +/- 4.1 kg/m(2) and the apnea-hypopnea index was 37.1 +/- 16.3/h. Prior to treatment, memory performances of OSA patients were altered. In an intention-to-treat analysis, memory deficits were not significantly improved after six weeks of effective CPAP compared to sham CPAP treatment. Verbal episodic, procedural, and working memory scores were comparable between both groups. Conclusion: Using cautious methodology in comparing effective CPAP to sham CPAP and a well-defined set of memory assessments, we did not find improvement in memory performance after six weeks of treatment. (C) 2016 Elsevier B.V. All rights reserved.