Risk of somatoform and sleep-related disorders in Parkinson's disease: A nationwide matched cohort study

Parkinson's disease (PD) is associated with diverse non-motor symptoms, including sleep-related and somatoform disorders, but population-based evidence on their long-term risk after PD diagnosis remains limited.

We conducted a nationwide retrospective matched cohort study using the Korean National Health Insurance Service National Sample Cohort (2012-2023). Individuals with incident PD (ICD-10 G20) were propensity score-matched 1:5 to controls. Incident sleep disorders (F51 or G47), somatoform disorders (F45), and a combined outcome were identified, and risks were evaluated using Cox proportional hazards models.

The matched cohort included 3800 patients with PD and 19,000 controls. The incidence rate of the combined outcome was higher in the PD group than in controls (64.8 vs. 32.9 per 1000 person-years; incidence rate ratio 1.97, 95% CI 1.82-2.14). In fully adjusted models, PD was associated with an increased risk of sleep disorders (adjusted hazard ratio 2.26, 95% CI 1.94-2.64), whereas the association with somatoform disorders was attenuated (1.39, 95% CI 0.99-1.95).

PD was associated with a markedly increased long-term risk of sleep disorders, while evidence for somatoform disorders was less definitive. These findings support early screening for sleep disorders following PD diagnosis.