Australian researchers who found a cluster of Parkinson's disease cases in Victoria's north-west say there needs to be an investigation into a possible link to pesticides used by farmers.
The study by Monash University and the Florey Institute of Neuroscience and Mental Health found rates of Parkinson's disease were between 34 and 78 percent higher than average in Buloke, Horsham, Northern Grampians and Yarriambiack.
The areas were exceptions to the rule that Parkinson's does not differ between urban and rural locations, the researchers said.
Barley and pulses - chickpeas, broad beans, lentils and vetches - are farmed in the four regions.
The researchers said further study was needed to investigate a possible link between those farming practices and the risk of Parkinson's.
Professor Ashley Bush said other studies had reported a greater risk of Parkinson's in rural areas.
"That has been linked to the use of certain sorts of pesticides, and you can generate Parkinson's disease in an animal by exposing it to certain types of pesticides," he said.
"So that's one question that we have to ask."
Parkinson's Victoria chief executive Emma Collin said understanding what caused Parkinson's could help researchers find a cure for the disease.
"Parkinson's currently affects over 27,000 people in Victoria, and we welcome investment in research projects to learn more about possible causes," she said.
"This new report - focusing on one possible cause - suggests we should be exploring the potential link between the use of pesticides used in farming of pulses and an increased risk of Parkinson's."
The research was released as part of the 'InSearch: Parkinson's Research' series.
A full report will be published later this year.