Introduction: Obstructive sleep apnea (OSA) is common among patients with Alzheimer's disease (AD). Untreated OSA exacerbates the cognitive and functional deficits. Continuous positive airway pressure (CPAP) has recently been shown to have beneficial effects on cognition in AD. Little attention has focused on the long-term benefits of CPAP in these patients.
Methods: This was an exploratory study of sustained CPAP use (mean use = 13.3 months, SD = 5.2) among a subset of participants from an initial 6-week randomized clinical trial (RCT) of CPAP in patients with mild to moderate AD. Follow-up included 5 patients who continued CPAP (CPAP+) after completion of the RCT and 5 patients who discontinued CPAP (CPAP-), matched by time of completion of the initial study. A neuropsychological test battery and sleep/mood questionnaires were administered and effect sizes were calculated.
Results: Even with a small sample size, sustained CPAP use resulted in moderate-to-large effect sizes. Compared to the CPAP- group, the CPAP+ group showed less cognitive decline with sustained CPAP use, stabilization of depressive symptoms and daytime somnolence, and significant improvement in subjective sleep quality. Caregivers of the CPAP+ group also reported that their own sleep was better when compared to the final RCT visit and that their patients psychopathological behavior was improved.
Conclusion: The results of this preliminary study raise the possibility that sustained, long-term CPAP treatment for patients with AD and OSA may result in lasting improvements in sleep and mood as well as a slowing of cognitive deterioration. Prospective randomized controlled research trials evaluating these hypotheses are needed.