Obstructive sleep apnea (OSA) is more common with age, regardless of weight. OSA in elderly patients can contribute to daytime sleepiness and impair cognitive performance. OSA has even been associated with development of early dementia, called mild cognitive impairment. There is not a lot of data showing the effects of CPAP use on cognitive functioning in elderly patients. But that is just what this study sought to do.
The study population was a subset of a larger study, and participants were at least 65 years old. Participants received extensive neuropsychological testing at the start and end of the study period (6-10 years between the two time points). Participants had a sleep study at the beginning of the study and only those with severe OSA were included. The researchers then divided the participants into those that used CPAP therapy and those that did not. This was a smaller study, with only 126 subjects included, 33 of which used CPAP. Also, note that CPAP use was determined by the patient's self-report. In other words, CPAP use was not determined objectively by checking what the CPAP machine had recorded. So it's possible that CPAP use may have been over-estimated. The researchers also did not separate out CPAP use into the number of hours per night - participants either did or did not report CPAP use. Interestingly, all of the CPAP users reported using CPAP for the minimal 4 hours per night. Finally, participants who used CPAP tended to have more severe OSA, were more overweight, and had more daytime sleepiness. There was no difference in age, gender, or level of education in those that used CPAP versus those that did not.
The results showed that subjects with OSA had a more severe deterioration of cognitive function and memory over time. Also, CPAP therapy helped preserve some cognitive functions like memory, attention, and decision making ability. The authors concluded that long term CPAP use is associated with a protective effect on cognitive performance in elderly patients with severe OSA. They suggest that physicians who treat elderly patients consider screening for and treating OSA to help maintain cognitive performance.