Study finds early-onset Parkinson’s burden has more than doubled worldwide

by · News-Medical

A global analysis reveals sharp rises in early-onset Parkinson’s disease among younger adults, exposing widening geographic and sex-based disparities while pointing to environmental clues that require deeper investigation.

Study: Global regional and national burden and trends of early-onset Parkinson’s disease from 1990 to 2021. Image Credit: Lightspring / Shutterstock

Study findings identified significant increases in incidence, prevalence, and years lived with disability (YLDs) across the three decades under investigation, revealing that the global burden of EOPD has more than doubled over this period.

The study further elucidates distinct geographic hotspots in EOPD incidence, an expanding gender gap indicating higher estimated burden among males, and a moderate country-level association with regional agricultural pesticide use, underscoring the need for additional research and targeted public health interventions to better understand and reduce the disease burden across regions.

Background

Parkinson's disease (PD) is a progressive neurodegenerative disorder clinically characterized by debilitating motor symptoms, especially tremors, muscle rigidity, and postural instability. Global public health reports indicate that the prevalence of PD has risen at an unprecedented rate from approximately 3.1 million in 1990 to approximately 11.8 million in 2021.

PD has historically been considered a condition affecting the elderly (“late-onset PD”). Consequently, a large portion of the extant literature has focused on this late-onset variant.

However, early-onset Parkinson's disease (EOPD; defined in this analysis as PD among individuals aged 20-49 years) has gained increasing attention because it affects younger adults and remains less well characterized at the population level, presenting unique and understudied socioeconomic and psychological hazards.

This age-at-onset of EOPD generally coincides with prime working and family-building years, thereby resulting in prolonged disability and profound mental health challenges. Unfortunately, public health agencies previously lacked robust population-level estimates of the burden of EOPD, hindering the development of mitigation strategies.

About the study

The present study aimed to enhance public health knowledge of EOPD by first estimating the population-level burden of the condition across distinct geographic scales. The study leveraged data from the GBD 2021 study to assess EOPD patterns across 204 countries and territories from 1990 to 2021.

The study’s analyses specifically focused on individuals included in EOPD estimates between the ages of 20 and 49 and evaluated three primary endpoints: 1. Incidence (number of new estimated EOPD cases per year), 2. Prevalence (number of estimated EOPD patients alive during the years under investigation), and 3. Years lived with disability (YLDs).

These primary endpoints were tracked using the estimated annual percentage change (EAPC) in GBD data over the study period. To further understand the potential influences of economic development on disease distribution, study outcomes were cross-referenced against the Socio-Demographic Index (SDI). SDI is a composite marker measuring regional fertility rates, educational attainment, and per capita income.

Finally, to elucidate the potential impacts of environmental changes and policy implementation on disease distribution, GBD data were matched against the Food and Agriculture Organization of the United Nations Statistical Database (FAOSTAT) to calculate total pesticide application per area of cropland.

Statistical analyses primarily comprised mathematical decomposition models, which were used to isolate whether population growth, population age structure, age-specific prevalence, or disease severity were the dominant drivers of the changing disability numbers.

Study findings

The findings were consistent with a marked escalation of EOPD over the past 31 years, revealing that incidence rose 187% from 28,267 in 1990 to 81,047 in 2021. Prevalence estimates mirrored incidence metrics, rising 154% from 190,487 to 483,872.

When standardizing for age, the study found that incidence increased from 1.46 to 2.35 (EAPC = 1.42%), prevalence from 10.03 to 14.00 (EAPC = 1.09%), and YLD from 1.65 to 2.27 (EAPC = 1.05%) per 100,000 individuals globally.

The study further revealed a marked sex difference in PD’s demographic burden, finding that men were approximately 1.5 times more likely to develop EOPD than their female counterparts. Specifically, the study analyses estimated male prevalence at 16.74 per 100,000 versus 11.23 for females.

Geographically, middle and high-middle SDI zones were observed to experience the fastest EOPD growth rate, led by East Asia and Andean Latin America. At the national level, Peru, Bolivia, and Ecuador logged the highest age-standardized rates, while China and Norway showed some of the fastest national upward trends; China’s incidence EAPC was 2.55%.

Ecological correlation analyses indicated that EOPD rates correlated positively with total pesticide use per cropland area (rho = 0.41, p < 0.001 for incidence; rho = 0.34, p < 0.001 for prevalence). Decomposition analysis showed that while population growth drove rising disability metrics in low-income zones, escalating underlying prevalence rates were the primary drivers in middle and high-middle SDI regions.

Conclusions

The present study establishes EOPD as a growing global public health burden that varies by socioeconomic development and correlates with pesticide use. The distinct correlation with regional agricultural practices underscores the need for further investigation, improved exposure monitoring, and safer occupational environments, rather than confirming a direct causal effect of pesticide use.

Because the analysis relied on modeled GBD estimates and country-level pesticide-use data, the findings may be affected by underdiagnosis, underreporting, regional data quality differences, and ecological confounding. Therefore, the pesticide findings should be interpreted as associations rather than causal evidence.

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