Regular pesticide exposure may play a role in some cases of deadly motor neuron disease, Australian research suggests.
University of Sydney scientists have found some patients with the progressive paralysing disease have differences in a gene known as paraoxynase, involved in breaking down organo-phosphates.
Neurologist Roger Pamphlett said preliminary results from a survey of 900 Australians, including 300 people with motor neuron disease, suggested regular exposure to pesticides may increase a person's risk of developing the condition.
Although the findings are in line with northern hemisphere studies, he said the researchers wanted to confirm the results in a much larger sample of people, including 1,000 motor neuron patients, before they publish their data in a scientific journal.
A National Health and Medical Research Council grant will allow them to collect information from many more cases during the next five years.
The scientists have set up the first DNA bank in the southern hemisphere to investigate the environmental and genetic influences underlying motor neuron disease, which usually strikes people aged in their 50s and 60s.
Population-based studies of disorders such as schizophrenia have suggested environmental influences on diseases may differ between hemispheres.
Little is understood about the causes of motor neuron disease which begins with either muscle weakness, muscle twitching or difficulty in speaking and progressively leads to paralysis.
Most patients die within two to five years of diagnosis.
Around 1,000 Australians are living with the condition at any one time.
Associate Professor Pamphlett said the DNA bank was the first to cover an entire continent and was expected to provide new insights into motor neuron disease.
He said the only treatment at the moment was a drug called Riluzole which increased a person's lifespan by "a few months".
"It does work but the effects are modest. The treatment can slow it down but can't stop it or reverse it," Prof Pamphlett said in an interview.
He said unlike the northern hemisphere studies, the Australian research had found no links between motor neuron disease, smoking and what season people were born in.
Prof Pamphlett said like many other conditions, motor neuron disease was not likely to be caused by a single gene or environmental factor.
"Our study seems to be the first hint that paraoxynase could be involved but it isn't the whole story because it doesn't explain all the cases," he said before addressing the
Australian Neuroscience Society's annual meeting in Sydney. "There could be viruses involved that attack motor neurons and perhaps some people don't have the right genes to protect against those viruses.
"That's another thing we're looking at."
By learning more about the causes of motor neuron disease, scientists hope to be able to develop better treatments.
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