Obstructive sleep apnea increases risk of developing Alzheimer's

Low-quality sleep can negatively impact one's overall health. Elderly people who aren't catching enough quality shut-eye may be vulnerable to long-term neurodegenerative damage. According to a new study published by the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine (AJRCCM), obstructive sleep apnea (OSA) may increase elderly individuals' risk of developing Alzheimer's disease.  

According a release, researchers reported that biomarkers for amyloid beta (Ab), the plaque-building peptides associated with Alzheimer's, increased over time in elderly adults with OSA as the condition worsens. Therefore, individuals with more apneas per hour have greater accumulation of brain amyloid over time, according researchers. 

"Several studies have suggested that sleep disturbances might contribute to amyloid deposits and accelerate cognitive decline in those at risk for AD," said Ricardo Osorio, MD, lead author and assistant professor of psychiatry at the New York University School of Medicine. "However, so far it has been challenging to verify causality for these associations because OSA and AD share risk factors and commonly coexist." 

Alzheimer's currently affects five million Americans over the age of 55. Depending on how OSA is defined, it afflicts 30 to 80 percent of the American elderly population. The close yet distinct associations between OSA and AD biomarkers longitudinally was the primary focus of the study.  

Specifically, to analyze whether amyloid deposits in the brain increase over time in relatively healthy elderly participants with OSA, Osorio and his team evaluated 208 individuals between the ages of 55 to 90 with determined normal cognitive function. According to the study, researchers performed lumbar punctures to obtain cerebrospinal fluid soluble Ab levels from all participants and then used PET scans to measure Ab deposits directly in the brain in a subset of participants.

Researchers found more than half the 208 participants had OSA, which confirmed their original hypothesis that an increase in amyloid deposits in the brain is correlated with patients who have OSA. However, the study didn't find that the severity of OSA predicted future cognitive deterioration in health elderly adults.

Osorio encourages further development of imaging technology and treatment for sleep apnea to delay and possibly prevent the development of neurodegenerative disorders.  

"Results from this study, and the growing literature suggesting that OSA, cognitive decline and AD are related, may mean that age tips the known consequences of OSA from sleepiness, cardiovascular, and metabolic dysfunction to brain impairment," Osorio said. "If this is the case, then the potential benefit of developing better screening tools to diagnose OSA in the elderly who are often asymptomatic is enormous." 

This research was supported by The National Institutes of Health, Foundation for Research in Sleep Disorders, the American Sleep Medicine Foundation and Friedman Brain Institute.