Global, Regional, and National Burdens of Parkinson's Disease in Adults Aged 20-50 Years, 1990-2021: A Cross-Sectional Study.

Background and Aims: Early-onset Parkinson's disease (EOPD), characterized by symptom manifestation between the ages of 20 and 50 years, imposes substantial clinical, psychosocial, and economic burdens. We evaluated the global, regional, and national burdens of EOPD from 1990 to 2021, emphasizing trends in incidence, prevalence, mortality, and disability-adjusted life years (DALYs) and projected future trajectories to 2050. Methods: Using age-standardized rates (ASRs) and absolute numbers from the Global Burden of Disease 2021 study across 204 countries, this analysis covers incidence, prevalence, deaths, and DALYs from 1990 to 2021. we analyzed temporal trends via Joinpoint regression. A decomposition analysis was used to quantify the contributions of aging, population growth, and epidemiological shifts. Bayesian Age-Period-Cohort modeling projected the future burden. Health inequalities were assessed using the intercept, slope, and concentration indices. Results: Globally, the incidence and prevalence of EOPD increased steadily, with ASRs reaching 2.35 and 14 per 100,000, respectively, by 2021. Males had a 1.5-fold higher incidence rate than females. The 45-50 age group exhibited the highest burden (age-standardized incidence rate: 8.98 per 100,000). Southeast Asia, East Asia, and Oceania had the highest regional burden (age-standardized incidence rate: 3.61 per 100,000). The high-middle sociodemographic index (SDI) regions showed the fastest incidence growth (estimated annual percentage change [EAPC]: 2.05). Global deaths declined (EAPC: -0.42), but DALYs increased in the low-middle SDI regions (EAPC: 0.32). This decomposition was attributed to aging and population expansion. Health inequalities indicated that high SDI regions exhibited a high burden of incidence but a low burden of mortality. Conclusion: The escalating burden of EOPD necessitates policies targeting modifiable risks (e.g., pesticide regulation), equitable access to healthcare, and early diagnosis. Genetic studies, occupational safety measures, and global health collaborations are vital to mitigate future impacts.