Research reveals regional and demographic differences in Parkinson’s disease in the Netherlands

This study did not find specific clusters of Parkinson’s cases in areas typically associated with high agricultural activity or poor air quality.
This does not mean that the environment plays no role. The pattern observed on the map suggests that environmental factors do contribute to the development of Parkinson’s. Parkinson’s arises from an interplay of many factors, each contributing only part of the risk. As a result, no clear clusters appear on the map.

Important to know:

• The risk of Parkinson’s builds up over decades.

• People move, change jobs, and adjust their lifestyles during that long period.

• Environmental exposures change over time.

• This study examined groups of people, not individual exposure.

The strength of this study is that, for the first time in the Netherlands, the number of new Parkinson’s diagnoses has been examined in a reliable and systematic way. It is therefore an important starting point for future research. Individual exposure to environmental factors was not assessed in this study; this is being addressed in ongoing research (OBO2 and PD PEST).

No, we cannot draw that conclusion. The study shows that no single factor explains everything. Previous studies have shown that air pollution and occupational pesticide exposure increase the risk of Parkinson’s. These effects are not always visible on a map because exposure can vary greatly within the same region—especially in a densely populated country like the Netherlands. Environmental factors remain relevant, even if no dominant factor appears on the map. Parkinson’s risk appears to be shaped by the combination of multiple (environmental) factors.

No, this study cannot tell us that. Although it did not show higher Parkinson’s rates in agricultural regions, this does not mean pesticides are automatically safe.
The study looked at diagnoses between 2017 and 2022 and found no clear link with specific agricultural regions. This may be because:

• The Netherlands is densely populated.

• Air pollution—mainly seen in cities—is also a major risk factor.

This makes differences between urban and rural areas less visible. Earlier international studies do show a link between occupational pesticide exposure and Parkinson’s. For people living near agricultural areas, international studies provide cautious indications of increased risk, but in the Netherlands there is no clear evidence yet.
This research is a starting point: follow-up studies like OBO2 and PD-PEST examine exposures much more accurately at the individual level.

It means that the rate at which new patients are diagnosed each year is neither increasing nor decreasing.
However, the total number of people living with Parkinson’s is clearly growing. This is due to:

• Ageing: more people live to older ages.

• People live longer with Parkinson’s thanks to improved care, including treatment by Parkinson’s specialists, such as those connected to the national ParkinsonNet.

• Better recognition of other conditions (called atypical parkinsonism) that used to be mistaken for Parkinson’s.

It is cautiously positive that the Netherlands does not see an increase in new diagnoses per year—unlike China and the United States. But Parkinson’s remains a serious condition with major impact.

Additional research is essential—and is already being conducted.
Now that we know where Parkinson’s occurs, we can study why. Ongoing studies (OBO2 and PD-Pest) examine in detail and at the individual level:
 

• Past exposure to substances (via questionnaires) and current exposure (via body and household dust measurements)

• Air quality and pesticide levels around the home

• Substances found in household dust or in the body (blood and stool)

• Occupational exposure, through work-history questions

• Lifestyle factors such as physical activity

• Genetic predisposition

These studies combine all factors to better understand overall risk.

Yes, these are publicly available:

• Air pollution maps (RIVM)

• Land use and agriculture maps (e.g., bulbs and fruit cultivation) (ion Dutch)

• Overviews of livestock farming (in Dutch)

These maps do not show clear overlap with the distribution of Parkinson’s found in the current study.

We do not yet know. The striking differences—for example between the north of the Netherlands and Zeeland—currently have no clear explanation. Ongoing research involving people from all over the country aims to clarify this by examining genetics, environment, and lifestyle together.

No. The number of new diagnoses per year is stable, but the total number of people living with Parkinson’s is rising. This is because people live longer and survive longer with the disease. It is unclear whether age itself is a risk factor. The relationship with ageing may be explained by longer cumulative exposure to harmful substances over time.
 

Partly yes, partly no.

On one hand, the attention to pesticides is understandable. Some substances (e.g., paraquat and rotenone) have been linked to Parkinson’s, especially in people exposed at work. Evidence for this relationship has existed since the 1980s.

On the other hand, this new study shows that agricultural activity does not explain regional differences. The findings show that the environment plays a role in Parkinson’s, but also that multiple factors contribute. It is therefore not justified to focus solely on agricultural pesticides. Other factors—such as air pollution, heavy metals, and solvents—may also contribute.

There are several reasons:

• Exposure levels differ between countries. The first large map-based study (Québec, Canada) in the 1980s took place when more harmful substances were still used.

• Toxic substances linked to Parkinson’s—like paraquat—have been banned in the Netherlands for years but are still used in places like the United States.

• Other countries have different types of agriculture, such as vineyards in France.

• Differences in lifestyle and genetic background.

• Differences in diagnostic practices and data collection.

The Netherlands is not automatically comparable to these regions.

Identifying a single cause is complex and requires long-term, careful research. A single study showing only statistical associations cannot prove causation.

Therefore, the Netherlands needs multiple types of studies that can be compared with international research. When different studies point in the same direction, certainty grows.

Findings from population studies must be combined with laboratory research that examines how certain substances affect brain cells. This strengthens the overall picture.

Because full certainty is often unattainable, thorough safety assessments of chemical substances remain essential. Regulatory bodies such as EFSA and the Ctgb play a crucial role, and independent evaluation is increasingly important.

The map shows where diagnoses were made in the period 2017–2022. This does not mean that the region itself is the cause.

The figures are based on a person’s postcode at the time of diagnosis. We do not know how long someone lived there or what exposures they had earlier in life. Because the delay between exposure and diagnosis can span decades, the cause may lie elsewhere.

Regional differences may also stem from lifestyle, age structure, diagnostic differences, or access to care. For many variations, the cause is unknown. Follow-up studies such as OBO2 and PD-Pest investigate this on an individual level.

These maps do not indicate personal risk. The data reflect group averages, and individuals within the same area can differ greatly in age, lifestyle, and health risks.
A higher number of diagnoses in a neighbourhood does not mean that everyone living there has a higher risk. Individual risks vary widely.