“Although a growing body of research suggests that obstructive sleep apnea (OSA) is a common, yet undiagnosed, risk factor for cognition impairment in older adults, few studies have examined whether positive airway pressure (PAP) therapy could protect those with OSA against developing dementia,” explains Galit Levi Dunietz, MPH, PhD.  “Given the high public health impact of dementia syndromes, such as Alzheimer’s disease (AD), and lack of effective treatments for dementia, studies that determine whether treatment of other common risk factors for dementia, such as OSA, are needed.”

For a paper published in Sleep, Dr. Dunietz, Tiffany J. Braley, MD, MS, and colleagues aimed to examine associations between PAP therapy adherence and 3-year incidence of Alzheimer’s disease, mild cognitive impairment (MCI), or dementia not-otherwise-specified (DNOS) in a large sample older adults diagnosed with OSA to determine if PAP use reduced the risk of subsequent diagnosis of AD, MCI, and DNOS when compared with no PAP therapy.

Medicare claims data from more than 50,000 Medicare beneficiaries—including 59% men, 90% non-Hispanic Whites, and 62% younger than 75—were utilized. ICD-9 diagnostic codes were used to identify neurocognitive syndromes that were diagnosed between 2011 and 2013. Associations between PAP therapy or adherence and new AD, MCI, and DNOS diagnoses were estimated using logistic regression models, adjusted for demographic and health characteristics. “In order to account for temporality, we excluded those with dementia, MCI or DNOS diagnosis at baseline and followed participants for 3 years,” Dr. Dunietz says.

PAP Therapy May Reduce Dementia Risk

The majority (78%) of beneficiaries with OSA were prescribed PAP treatment, with 74% showing evidence of adherence to this treatment. In adjusted models, PAP treatment was associated with lower odds of incident diagnoses of AD and DNOS (odds ratio [OR], 0.78 and 0.69, respectively). Lower odds of MCI, approaching statistical significance, were also observed among PAP users (OR, 0.82). PAP adherence was associated with lower odds of incident diagnoses of AD (OR, 0.65) (Table).

These findings suggest that PAP therapy may reduce the risk of dementia among older adults with OSA, according to Dr. Braley. “Given these emerging findings and other known health consequences of OSA, physicians should maintain a low threshold to screen for OSA in older adults and treat it if present,” she says.

Pulmonologists Positioned to Play Key Role

The study findings raise the possibility that treatment of OSA may offer new opportunities to improve cognitive outcomes in older adults, Dr. Braley says. “If a causal pathway exists between OSA treatment and dementia risk, pulmonologists are positioned to play a key role in the health and cognitive well-being of older adults through effective diagnosis and treatment of OSA.”

As with any observational study, causality and its direction cannot be established beyond doubt, according to Dr. Dunietz. “While OSA diagnosis preceded the diagnosis of dementia, reverse causality cannot be fully ruled out,” she says. “The typical age of OSA onset greatly precedes the typical age of dementia onset, but future studies over longer time intervals may be needed to confirm that the association in the present data between OSA treatment or adherence and lower incidence of dementia does not arise because dementia impedes subsequent OSA treatment and adherence.”