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Abstract
Objectives Parkinson’s disease (PD) has become a public health concern with global ageing. With a focus on PD, this study sought to project its burden and trends at the national, regional and worldwide levels between 1990 and 2021.
Study design Population-based study.
Methods The Global Burden of Disease (GBD) 2021 provided the PD burden data. The GBD data are considered globally and regionally representative, as it integrates multiple data sources and employs standardised estimation methods. The age-standardised rate (ASR) and estimated annual percentage change (EAPC) were used to estimate trends in the incidence, prevalence, mortality and disability-adjusted life years (DALYs) of PD from 1990 to 2021. ASR was used to calculate the EAPCs using a linear regression model. A Bayesian age-period-cohort model was used to predict future trends up to 2046.
Results Globally, the overall ASR of PD incidence, prevalence, DALYs and mortality increased from 1990 to 2021. The EAPCs were 1.09 (95% CI: 1.07 to 1.11) for incidence, 1.52 (95% CI: 1.49 to 1.54) for prevalence, 0.32 (95% CI: 0.28 to 0.36) for DALYs and 0.18 (95% CI: 0.13 to 0.23) for mortality. The incidence, prevalence, mortality and DALYs of PD in 2021 were higher in men than in women. The age-standardized incidence rate (ASIR) was 18.52 per 100 000 in men and 12.92 per 100 000 in women (EAPC: 1.11, 95% CI: 1.09 to 1.13 vs 1.07, 95% CI: 1.05 to 1.09). The age-standardized prevalence rate (ASPR) was 157.42 per 100 000 in men and 121.84 per 100 000 in women (EAPC: 1.70, 95% CI: 1.67 to 1.73 vs 1.25, 95% CI: 1.22 to 1.27). The ASMR was 6.57 per 100 000 in men and 3.59 per 100 000 in women (EAPC: 0.21, 95% CI: 0.14 to 0.28 vs −0.01, 95% CI: −0.04 to 0.03). The ASDR was 97.12 per 100 000 in men and 81.23 per 100 000 in women (EAPC: 0.37, 95% CI: 0.33 to 0.42 vs 0.14, 95% CI: 0.10 to 0.18). From 1990 to 2021, the burden of PD remained consistently higher in men than in women, with the gender difference widening with age. The prevalence, incidence, DALYs and mortality rates of PD increased with age before declining, peaking in the 80–84 age group for prevalence and incidence, while peaking in the 90–94 age group for mortality. DALY rates peaked in the 85–89 age group. The ASR of incidence and prevalence increased significantly in Norway (EAPC=3.39, 95% CI: 3.15 to 3.64; EAPC=5.04, 95% CI: 4.65 to 5.43). Lesotho was the nation with the highest rise in age-standardised DALYs for PD (EAPC=1.67, 95% CI: 1.41 to 1.93). The United Arab Emirates had the fastest increase in age-standardised mortality for PD (EAPC=1.98, 95% CI: 1.24 to 2.71). The global ASPR of PD is projected to show a continuous upward trend.
Conclusions From 1990 to 2021, there were rising trends in the prevalence and burden of PD in most areas and nations worldwide. Our research indicates that the management and control of PD need significant improvement, particularly in light of the ageing population.
- Prevalence
- Mortality
- Aging
Data availability statement
All data relevant to the study are included in the article or uploaded as supplementary information.
This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.
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STRENGTHS AND LIMITATIONS OF THIS STUDY
This study used the Global Burden of Disease (GBD) 2021 database, which provides a comprehensive and standardised assessment of Parkinson’s disease (PD) burden across 204 countries and territories.
The use of age-standardised rates and estimated annual percentage change allowed for robust comparisons of trends in PD incidence, prevalence, mortality and disability-adjusted life years.
The Bayesian age-period-cohort model was applied to predict future trends, enhancing the study’s methodological rigour.
The reliance on secondary data from the GBD study may introduce reporting biases and inconsistencies in data collection across different countries.
The study could not account for individual-level risk factors or genetic predisposition due to the ecological nature of the analysis.
Introduction
Parkinson’s disease (PD) is the second most prevalent neurodegenerative illness. It is characterised by low dopamine levels because the substantia nigra loses dopaminergic neurons.1 Among neurological diseases, PD has shown the fastest increase in frequency and impairment in recent years, making it one of the primary causes of disability globally2 (PMID: 38745974). Furthermore, there was a 155.5% global increase in the prevalence of PD between 1990 and 2019.3 Additionally, there was a significant increase in the PD-attributable disability-adjusted life year (DALY) rates, along with increases in the sociodemographic index (SDI).4 It was discovered that PD was more common in men and that its frequency rose with age, culminating in the 85–89 and 90–94 age ranges for men and women, respectively.4
Nevertheless, no study has examined changes in mortality, disability and prevalence during the previous generation globally and in each nation in 2021. Our goal was to investigate the variations in counts and age-standardised rates (ASR) of PD between 1990 and 2021 in terms of incidence, prevalence, disability and mortality.
Method
Definitions
PD is a progressive, degenerative, chronic neurological disorder characterised by motor symptoms such as tremors, bradykinesia, rigidity and postural instability. According to the International Classification of Diseases, 10th Revision (ICD-10), PD is classified under codes G20, G21 and G22 (WHO, 2019).
Study design and data sources
The Global Burden of Disease (GBD) 2021 study employed a consistent and standardised methodology to estimate population, fertility, morbidity and mortality across 204 countries and territories. It integrates multiple data sources, including vital registration systems, hospital records and surveys, ensuring comprehensive coverage. However, data availability varies across regions, particularly in low-income countries where reporting may be limited or inconsistent. In such cases, GBD applies statistical modelling and imputation techniques to estimate missing values, enhancing data comparability across different settings. While these methods improve data reliability, estimates for data-limited regions may have greater uncertainty. In-depth details on this research are available in GBD 2021.5 The GBD research found that there were notable differences in the cause-of-death and prevalence data for PD, in contrast to most other disorders. In order to increase estimation accuracy, the GBD research team worked collaboratively to replicate PD mortality and morbidity estimates. Additional information is available in the literature.3 5 6
From 1990 to 2021, we retrieved demographic data and PD data for 204 countries and territories. Each estimate was provided as a rate per 100 000 people and as counts per thousand. Using an ordered set of 1000 drawings, the 2.5th and 97.5th percentiles were used to calculate the 95% uncertainty interval (UI). The GBD world population age standard was used to calculate age-standardised populations. The SDI is a measure of socioeconomic development that considers the total fertility rate for people under 25 years old, the mean years of education for those over 15 and the mean per capita income. The SDI ranges from 0 (least developed) to 1 (most developed). Incidence, prevalence, DALYs and mortality statistics have been collected. Since the data were available to the public, neither ethics approval nor informed permission was needed for the study. The GATHER Guidelines for Accurate and Transparent Health Estimates Reporting were followed by the cross-sectional study.7
Statistical analysis
To describe the worldwide burden of PD, a descriptive analysis was conducted. Through the use of the 95% UI retrieved from the database, we compared the age-standardised incidence, age-standardised prevalence, age-standardised mortality and age-standardised DALYs of PD across various age groups, sexes, regions and nations. We adopted a unified analytical framework across these subgroups, thereby eliminating redundant descriptions of trends. The estimated annual percentage change (EAPC) was calculated to quantify temporal changes from 1990 to 2021, with an EAPC (and its 95% CI) above 0 indicating an increasing trend and below 0 indicating a decreasing trend and values overlapping 0 indicating stability.
Furthermore, 54 regions were categorised into four groups using a hierarchical cluster analysis according to the temporal patterns in the PD ASR aetiologies. The clustering process was conducted using Ward’s method with Euclidean distance as the similarity measure. Prior to clustering, ASR values were standardised to ensure comparability across regions. The optimal number of clusters (four) was determined using the Elbow method. Finally, a Bayesian age-period-cohort (BAPC) model was employed to forecast PD trends from 2022 to 2046. Data analyses were performed using R Studio and R software (version 4.3.1) (R Core Team, 2023).
Results
Global level
In 2021, PD accounted for 1.34 million incident cases globally. Over the previous 30 years, the age‐standardised incidence rate has progressively grown (11.24 per 100 000 population (95% UI: 10.01–12.49) in 1990 and 15.63 per 100 000 population (95% UI: 14.03–17.39) in 2021), with an EAPC of 1.09 (95% CI: 1.07 to 1.11) (table 1, online supplemental table S1). The global prevalence of PD increased by 274%, from 3.15 million cases in 1990 to 11.77 million in 2021. Correspondingly, the age‐standardised prevalence rate rose by 28% (from 86.28 per 100 000 to 138.63 per 100 000; EAPC=1.52, 95% CI: 1.49 to 1.54). In contrast, changes in DALYs and mortality were less pronounced, with DALYs increasing from 81.48 per 100 000 in 1990 to 89.59 per 100 000 in 2021 (EAPC=0.32, 95% CI: 0.28 to 0.36) and mortality rising from 4.62 per 100 000 to 4.81 per 100 000 (EAPC=0.18, 95% CI: 0.13 to 0.23) (table 2, online supplemental table S2).
Supplemental material
Age-standardised incidence and prevalence of Parkinson’s disease in 2021 and EAPC from 1990 to 2021 globally and in different age groups and genders
Age-standardised DALYs and mortality of Parkinson’s disease in 2021 and EAPC from 1990 to 2021 globally and in different age groups and genders
Global trends by sex
Globally, both male and female PD cases increased between 1990 and 2021. Male prevalence increased from 1.56 million to 6.44 million, while female prevalence increased from 1.59 million to 5.33 million (online supplemental table S1). Men exhibited a faster increase in prevalence (EAPC=1.70 vs 1.25 in women) and a higher age-standardized incidence rate (ASIR) increase (EAPC=1.11, 95% CI: 1.09 to 1.13) compared with women. Additionally, the increase in age-standardised DALYs was more pronounced in men (EAPC=0.37) than in women (EAPC=0.14). Notably, while the age-standardised mortality rate slightly decreased in women (from 3.62 to 3.59 per 100 000; EAPC=−0.01, 95% CI: −0.04 to 0.03), it increased in men (from 6.28 to 6.57 per 100 000; EAPC=0.21, 95% CI: 0.14 to 0.28) (table 2). Incidence, prevalence, mortality and DALYs for PD all increased between 1990 and 2021, as illustrated in figure 1. The burden in males continuously exceeded that in females, with the gender gap growing larger with age.
Age-standardised rates of incidence, prevalence, mortality and disability-adjusted life years for Parkinson’s disease by gender from 1990 to 2021.
Global trends by age subgroup
PD incidence, prevalence, DALYs and mortality rates increased across most age groups, with a pattern of rising cases followed by a decline in the oldest groups. Specifically, the highest incidence and prevalence were observed in the 80–84 age range, mortality peaked in the 90–94 age group and DALYs reached a maximum in the 85–89 age group (tables 1 and 2, online supplemental tables S1 and S2, figure 2, online supplemental figure S1).
Age-standardised rates of incidence, prevalence, mortality and disability-adjusted life years for Parkinson’s disease in different age groups from 1990 to 2021.
Global trends by sociodemographic index
In 2021, the countries with a high-middle SDI had the highest incidence and prevalence of PD (173.39 per 100 000 population). From 1990 to 2021, the age-standardised prevalence of PD increased globally, with a particularly significant rise in high-middle SDI countries (EAPC=1.61, 95% CI: 1.90 to 1.57). The age-standardised incidence rate increased across all SDI areas, with the middle SDI region showing the most pronounced rise (EAPC=1.47, 95% CI: 1.44 to 1.51). In contrast, PD-related mortality decreased in high-middle and middle SDI groups, whereas the age-standardised DALYs increased across all SDI subgroups. In 2021, countries with a high-middle SDI also exhibited the highest DALYs (94.16 per 100 000 population), while those with a low SDI had the lowest (83.09 per 100 000) (table 3, online supplemental tables S1–S3, figure 3, online supplemental figure S2).
Age-standardised incidence and prevalence of Parkinson’s disease in 2021 and EAPC from 1990 to 2021 in different sociodemographic index (SDI) regions and geographic regions
Age-standardised rates of incidence, prevalence, mortality, DALYs for Parkinson’s disease in different SDI areas from 1990 to 2021.
Regional trends
Among 21 geographic regions in 2021, East Asia had the highest age-standardised prevalence of PD (243.46 per 100 000). The age-standardised prevalence of PD increased in almost all regions, except in Eastern Europe, which showed a slight decline (EAPC=−0.04, 95% CI: −0.15 to −0.07). East Asia experienced the fastest rise in prevalence (EAPC=3.17, 95% CI: 3.04 to 3.30), whereas Central Europe exhibited the slowest increase (EAPC=0.26, 95% CI: 0.23 to 0.29). Additionally, East Asia recorded the largest number of incident cases in 2021 (0.52 million), while Oceania had the fewest (0.69 thousand). The ASIR varied from 8.23 per 100 000 in high-income Asia Pacific to 24.16 per 100 000 in East Asia. These regional comparisons, along with trends in DALYs and mortality (eg, DALYs: 107.68 per 100 000 in East Asia vs 60.24 per 100 000 in high-income Asia Pacific; mortality: greatest decline in East Asia (EAPC=−0.73, 95% CI: −0.89 to −0.58) and greatest increase in high-income North America (EAPC=1.36, 95% CI: 1.25 to 1.48)) (EAPC=1.36, 95% CI: 1.25 to 1.48) (table 3, online supplemental tables S1–S3, online supplemental figure S3 and S4).
Based on the temporal trends associated with PD ASRs, a hierarchical cluster analysis was performed to identify regions. These areas were grouped into four groups based on comparable patterns. The colours assigned to each group were as follows: major decline, constant or moderate decrease, significant rise, and minor increase (online supplemental figure S5).
National trends
At the national level, age-standardised prevalence rates of PD varied more than fivefold, with the highest rates generally observed in China (245.73 per 100 000) and the lowest in Somalia (49.02 per 100 000). The ASIR ranged from 7.28 per 100 000 in Japan to 24.34 per 100 000 in China. Norway exhibited the largest increase in prevalence (EAPC=5.04, 95% CI: 4.65 to 5.43) and the highest increase in incidence (EAPC=3.39, 95% CI: 3.15 to 3.64), while Italy showed a decline in incidence (EAPC=−1.16, 95% CI: −1.36 to −0.96). Moreover, Cyprus demonstrated the greatest reduction in DALYs (EAPC=−2.55, 95% CI: −2.77 to −2.33), Lesotho had the largest rise in DALYs (EAPC=1.67, 95% CI: 1.41 to 1.93), and Honduras recorded the highest DALYs (157.67 per 100 000) as well as the highest age-standardised mortality (9.65 per 100 000). The United Arab Emirates exhibited the fastest increase in mortality (EAPC=1.98, 95% CI: 1.24 to 2.71), and Cyprus experienced the fastest decline in prevalence (EAPC=−3.32, 95% CI: −3.61 to −3.03) (table 3, online supplemental tables S1–S3, figure 4, online supplemental figure S6 and S7).
EAPCs of incidence, prevalence, mortality, DALYs for Parkinson’s disease at the national level from 1990 to 2021.
Global trends of PD predicted by the BAPC model
The global ASPR of PD was projected to show a continuous upward trend. The ASPR of males and females was projected to be 206.00 per 100 000 (95% UI: 82.07–329.94) and 149.44 per 100 000 (95% UI: 68.63–230.25) in 2046, respectively. The incidence rate of PD in both genders is projected to increase, with the ASIRs for females and males, with populations increasing from 13.60 per 100 000 (95% UI: 11.96–15.25) and 21.72 per 100 000 (95% UI: 18.80–24.63) in 2029 to 15.59 per 100 000 (95% UI: 6.82–24.35) and 24.06 per 100 000 in 2046 (95% UI: 9.26–38.86). In general, the age-standardised death and DALY rates of PD in both sexes are predicted to decrease from 2020 to 2040. Sex differences persist, with men carrying a heavier disease burden than women (figure 5).
The predictions of global number of cases and age-standardised rates of incidence, prevalence, mortality and disability-adjusted life years (DALYs) for Parkinson’s disease over 24 years (2022–2046).
Discussion
Our study presented a comprehensive analysis of PD prevalence worldwide over the past 30 years. It revealed a significant increase in the age-standardised prevalence of PD from 1990 to 2021, yet death and DALY rates did not change significantly. The current study’s findings demonstrated that the age-standardised prevalence was 57.03% higher than in 1990, at 138.63 per 100 000 people. From the standpoint of age-standardised rates, the age-standardised incidence and prevalence rates of PD kept rising even after accounting for population ageing. Furthermore, earlier studies have shown that the prevalence, death and DALYs associated with PD peaked in older adults, and that men had greater rates of PD in almost all age categories, all of which are consistent with the findings of the current study.8 9
The increase in the prevalence of PD may be attributed to the following reasons. First, the ageing population is strongly linked to the increased prevalence of PD, which is a chronic but non-fatal condition. Despite constant incidence and similar mortality patterns to the general population, the extended disease duration and increased prevalence of PD are likely due to longer life expectancies among those affected.10 Underascertainment at older ages due to underdiagnosis, comorbidities or healthcare limitations in institutions could account for the decline observed in the oldest age groups after the peak between 85 and 89 years of age. Second, better estimates of prevalence, DALYs and mortality after 1990 may have resulted from modifications in study techniques, the availability of higher quality studies and increased awareness of diagnosis.11 12 Door-to-door surveys, for instance, are less likely to overlook undiagnosed individuals who might otherwise go unnoticed in medical records.13 Third, environmental variables associated with the global industrialisation process may be responsible for the rise in the prevalence of PD. PD may become increasingly prevalent in high-middle SDI countries due to several environmental hazards associated with industrialisation, such as metals, solvents and pesticides.14–16 Fourth, declining smoking rates in some countries may contribute to the increasing prevalence of PD, though the causal relationship remains debated, with some studies suggesting that lower smoking prevalence could lead to a 10% rise in PD burden by 2040.17–20 Finally, variations in the incidence rates of PD may be caused by shifts in the prevalence of other recognised factors, such as head trauma,21 genetic predisposition,22 adherence to the Mediterranean diet,23–25 or undiscovered risk or protective factors.
According to our findings, men were considerably more likely than women to have PD-related prevalence, death and DALY rates. Gender inequalities may arise from variations in the frequency of exposure to specific risk factors. Moreover, oestrogen may have neuroprotective benefits for females.26
The high-middle SDI area, where the number of PD patients increased the most, showed the highest growing trend in ASR of prevalence across the SDI quintiles. East Asia showed the strongest rising trends in ASR prevalence when compared with other locations; this was presumably due to ageing and population growth.27 Significant advancements have also been made in the social insurance and health systems.28 The changing trends across countries were explained by the substantial correlation between the prevalence trends and the morbidity of PD. Even though the ASR of DALYs in high-income Asia Pacific was the lowest in 2021, high-income North America experienced the fastest increase in the ASR of DALYs. Improved treatment options that are now accessible and prolong the course of the disease are likely responsible for the higher incidence of PD in industrialised nations. Because of the longer life expectancy and greater frequency of long-term mental problems, such as psychosis, sadness and anxiety, the striking increase in the illness load may also be linked to increased disability.29 The Mediterranean diet has been linked to a decreasing trend in ASIR in Italy, possibly due to its preventive effects on health and age-related disease.30–32
China has the highest incidence and prevalence rates of PD. The ageing population, an increasing proportion of elderly individuals, improvements in medical care, and evolving screening and diagnostic methods have all contributed to enhanced recognition and diagnosis of PD among patients and medical professionals. Concurrently, the country’s economic growth has led to heightened exposure to industrial pollutants such as heavy metals and solvents, and the persistent overuse of pesticides poses a significant risk.33 34 These factors are contributing to the increased incidence and prevalence of PD in China.
The predictive model suggests that the incidence and prevalence rates will gradually increase, whereas ASDR and ASMR are projected to decline. Therefore, it is important that sufficient preparation be made for the ageing of the population. The results suggested that proactive measures, such as civil health promotion plans, security and healthcare systems, and healthy lifestyle choices, should be implemented to address the issues brought on by PD.35–37
The study does, however, have a few drawbacks. First, PD is a heterogeneous illness with a range of symptoms, progression styles and concurrent cognitive deficits. Because of this, clinicians frequently misdiagnose PD, and a qualified, specialised physician is needed to accurately diagnose PD. The robustness and certainty of our results may have been impacted as a result. Second, we were unable to determine how the various risk variables affected the progression of PD because of the limitations of the GBD study. This highlights the importance of incorporating risk variables into future revisions of the GBD project. Third, future studies should consider the neurobiological mechanisms underlying PD development, including α-synuclein aggregation and Lewy body pathology, mitochondrial dysfunction, neuroinflammation and impaired dopamine neurotransmission, all of which have been implicated in PD pathogenesis.38–40
In conclusion, this study provides a comprehensive review of the prevalence of PD and its trends from 1990 to 2021 at the national, regional and global levels. The burden of PD has significantly increased in most countries and regions, suggesting that PD is becoming an increasing threat to global health. Given the rapidly ageing population, our findings indicate that more effective strategies are needed to mitigate the impact of PD.
Data availability statement
All data relevant to the study are included in the article or uploaded as supplementary information.
Ethics statements
Patient consent for publication
Ethics approval
Not applicable.
Acknowledgments
We thank all the study participants for their assistance and supports.
References
Footnotes
ML, XY and ZH contributed equally.
Contributors ML: project administration and drafting. XY: data analysis and validation. ZH: data analysis and visualisation. LY: data collection and collation. CNC: supervision and drafting and editing. All authors contributed to the writing and revisions of the paper and approved the final version. The guarantor is ML.
Funding This work was supported by (Quanzhou City Science and Technology Program of China) grant number (No. 2024 NY026) and (Startup Fund for scientific research, Fujian Medical University) grant number (No. 2023QH1125).
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Competing interests None declared.
Patient and public involvement Patients and/or the public were not involved in the design, conduct, reporting or dissemination plans of this research.
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