Untreated Sleep Apnea Linked to Doubled Parkinson’s Risk in Major Study

A landmark study from Oregon Health and Science University (OHSU) has revealed a significant association between untreated sleep apnea and an increased risk of developing Parkinson’s disease, with early treatment potentially offering protective benefits.

Researchers analyzed medical records of more than 11 million U.S. veterans aged 40 and older who were initially free of Parkinson’s disease. The participants were tracked for an average of nearly five years to determine who eventually developed the neurodegenerative condition.

The findings, published in JAMA Neurology, showed that veterans with untreated obstructive sleep apnea—a disorder characterized by repeated breathing interruptions during sleep—faced almost twice the risk of developing Parkinson’s compared to those without the sleep condition. This translated to approximately one to two additional Parkinson’s cases per 1,000 people over the five-year period.

“The results were surprising,” said Dr. Greg Scott, an Oregon-based pathologist and co-author of the study. “People who still got Parkinson’s but had been on CPAP had fewer fractures, fewer falls and lower mortality. We tested this rigorously and the result kept happening.”

Continuous positive airway pressure (CPAP) therapy emerged as a potential protective intervention in the research. Veterans who began CPAP treatment within two years of their sleep apnea diagnosis showed a 30% lower risk of developing Parkinson’s compared to those who delayed or never started therapy. This reduction amounted to approximately 2.3 fewer Parkinson’s cases per 1,000 individuals, suggesting that early CPAP treatment could prevent one Parkinson’s case for every 439 people treated over five years.

The study draws on comprehensive medical records from the Department of Veterans Affairs spanning from 1999 to 2022. Researchers controlled for multiple factors including age, sex, race, smoking history, and other health conditions to isolate the relationship between sleep apnea and Parkinson’s risk.

Several biological mechanisms may explain the link between sleep apnea and neurodegeneration, according to the researchers. Dr. Lee Neilson, OHSU neurologist and lead author of the study, explained: “If you stop breathing several times an hour and your oxygen levels are dropping… you’re essentially stunning those brain cells every time that is happening.”

The repeated oxygen deprivation characteristic of sleep apnea may damage neurons, trigger inflammation, and disrupt the brain’s waste-clearing processes, potentially allowing harmful proteins to accumulate in brain tissue. By stabilizing oxygen levels and improving sleep quality, CPAP therapy may mitigate these stresses and help protect brain tissue over time.

“The best strategy for a neurodegenerative disease is prevention and catching risk factors early, before the damage is done,” Scott emphasized.

While the findings suggest a compelling connection between sleep apnea and Parkinson’s risk, the researchers note important limitations to their work. As an observational study, it demonstrates correlation rather than causation. The research also lacked detailed data on participants’ CPAP adherence—how consistently they used their devices. Additionally, the study population consisted predominantly of older men, potentially limiting the generalizability of the results to other demographic groups.

The team also acknowledged that early signs of Parkinson’s, which often include sleep disturbances, might have led some individuals to receive a sleep apnea diagnosis in the first place, potentially complicating interpretation of the temporal relationship between the conditions.

This research adds to a growing body of evidence linking sleep disorders to neurological health and highlights the potential importance of early sleep apnea detection and treatment as a strategy for reducing neurodegeneration risk. For the estimated 30 million Americans affected by sleep apnea, many of whom remain undiagnosed, these findings may provide additional motivation to seek evaluation and treatment.