Researchers are conducting an investigation into the risk factors for Parkinson's disease.
It is widely recognised that an impaired sense of smell is an indicator of the illness and a team led by the Institute for Neurodegenerative Disorders and the University of Pennsylvania is studying whether a small test can help determine if people with no symptoms are susceptible to the disease.
As part of the study, 15,000 close relatives of Parkinson's patients will have their sense of smell tested with approximately 40 odours.
It is believed that Parkinson's patents can only recognise about 25 odours compared with a core of 35 in non sufferers.
"We believe that if you're a person who is going to develop Parkinson's, you'll also score lower than others," Dr Kapil Sethi said.
Based on the results of the test, the participants will be separated into two groups and observed for three to five years to assess whether or not they develop Parkinson's.
Dr Sethis added that the long term goal of the study is to develop prevention strategies once risk is established.
According to the Parkinson's Disease Society, approximately 10,000 people throughout the UK are diagnosed with Parkinson's each year.
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