Treating Sleep Apnea Early May Reduce Parkinson's Disease Risk by 31%

Parkinson's disease is the fastest-growing neurological disorder globally, yet evidence-based strategies to reduce its risk remain scarce. Obstructive sleep apnea (OSA), increasingly prevalent and known to cause chronic intermittent hypoxia, mitochondrial dysfunction, elevated alpha-synuclein, and reduced dopamine transporter availability, has been proposed as a potential upstream driver of neurodegeneration. Prior epidemiological evidence linking OSA to PD was conflicting and methodologically limited. This large-scale study sought to resolve that uncertainty and, uniquely, to test whether CPAP treatment modifies PD risk.

Researchers used the VA Corporate Data Warehouse EHR, covering January 1999 to December 2022, to study 11,310,411 veterans (mean age 60.5 years; 9.8% female). OSA was defined by ICD-10 code G47.33 with a validated positive predictive value of 94%. PD was defined using a high-specificity algorithm requiring ICD codes, at least 5 years of prior records, and two filled PD medication prescriptions (PPV 78.6%). Inverse probability of treatment weighting balanced groups on age, sex, race, and smoking, and all analyses adjusted for competing risk of death via cumulative incidence functions.

Veterans with OSA showed 1.61 additional PD cases per 1000 people at 6 years compared to those without OSA (HR 1.92; 95% CI, 1.55–2.38). This association persisted across multiple sensitivity analyses adjusting for BMI, vascular comorbidities, psychiatric conditions, REM sleep behavior disorder, traumatic brain injury, dopaminergic and neuroleptic medications, and healthcare utilization differences. Both mild and severe OSA were independently associated with elevated PD risk, with severe OSA demonstrating earlier onset of excess risk (year 1 vs year 5). Female veterans showed a strikingly higher hazard ratio (HR 4.24) compared to male veterans (HR 2.21).

For the CPAP analysis, 144,643 veteran records with documented CPAP data were examined. Veterans who initiated CPAP within 2 years of OSA diagnosis had a 31% lower risk of developing PD (HR 0.69; 95% CI, 0.56–0.85), with an absolute risk reduction of 2.28 cases per 1000 at 5 years. The number needed to treat to prevent one PD case was estimated at 439. This protective effect remained robust when a stricter CPAP adherence definition was applied (HR 0.65), and after adjusting for healthcare utilization bias using negative control outcomes.

These findings provide the largest and most methodologically rigorous evidence to date that OSA is an independent, modifiable risk factor for PD, and that early CPAP treatment attenuates that risk. Biological plausibility is supported by OSA's known effects on intermittent hypoxia, mitochondrial stress, and alpha-synuclein accumulation. The results suggest that systematic OSA screening and consistent CPAP adherence protocols could represent a meaningful, actionable strategy for PD prevention at the population level.