The Telegraph | Kate Devlin | Parkinson's sufferers are more likely to have significant levels of a pesticide in their body than healthy people, a new study has found.
Researchers believe that the chemical could act as a "trigger" to people already prone to develop the disease.
They hope that testing for the pesticide in the blood could someday identify patients at risk of developing the devastating neurological condition.
Around 120,000 people in Britain have Parkinson's, which occurs when nerve cells in the part of the brain that controls muscle movement become damaged or die.
Researchers found the pesticide beta-HCH in 76 per cent of people with Parkinson's, compared with 40 percent of healthy controls and 30 percent of those with Alzheimer's.
The chemical is a component of Lindane, a pesticide which has been banned in Britain since 2000, but stays in the body for decades.
"Much higher levels of the beta-HCH were in the air, water and food chain when the Parkinson's patients were in their 20s and 30s," said Dr Dwight German, from UT Southwestern Medical Centre, who led the study.
"Also, the half-life of the pesticide is seven to eight years, so it stays in the body for a long time. There's been a link between pesticide use and Parkinson's disease for a long time, but never a specific pesticide.
"This is particularly important because the disease is not diagnosed until after significant nerve damage has occurred. A test for this risk factor might allow for early detection and protective treatment.
"Some people with Parkinson's might have the disease because of exposure to environmental pesticides, but there are also genes known to play a role in the condition."
The study tested 113 volunteers, aged between 50 and 89, 50 of whom had Parkinson's, 20 had Alzheimer's and the rest were healthy.
The findings were reported in the Archives of Neurology journal.