Scientists suspect insecticide chemicals damage nerve cells in a vulnerable region of the brain, but cannot fully explain the link.
 Certain chemicals that an individual is exposed to in the environment may cause selective death of brain cells  |
Dr Lorene Nelson, Stanford University |
Another group of 541 people without the disease were asked similar questions and the two sets of answers compared.
Use of insecticides at home was associated with the greatest risk of developing the disease. Parkinson's patients were more than twice as likely to have been exposed to the chemicals than the healthy participants.
There was also an association with herbicides. However, exposure to insecticides in the garden, and fungicides, were not found to be risk factors.
The findings were presented at the American Academy of Neurology's annual meeting in San Diego, California.
Association
Dr Nelson said: "It is the first study to show a significant association between home pesticide use and the risk of developing Parkinson's disease.
"Certain chemicals that an individual is exposed to in the environment may cause selective death of brain cells or neurons."
Damage to nerve cells in a part of the brain called the basal ganglia leads to the muscle tremor and stiffness characteristic of the disease.
Parkinson's is caused when brain cells that produce an important neurotransmitter, or message-carrying chemical, are destroyed.
Dr Nelson said. "If we could understand why these neurons are being killed in certain circumstances, we can then try and prevent it."
Professor Adrian Williams, chairman of the Parkinson Disease Society's medical advisory panel, said: "This is the latest in a line of research which shows a suspected but as yet unproven link between pesticide exposure and development of Parkinson's disease.
"We welcome any further research on this subject."
