New Delhi, Nov. 23: Education and occupation appear to influence the risk of Parkinson’s disease, according to a new study that has hinted that the higher the education, the greater is the risk of this devastating brain disorder.

The study has shown that the risk of Parkinson’s disease rises with years of education, with the greatest risk in people with nine or more years’ education. The study has also found that, compared to the general population, physicians had the greatest increased risk for Parkinson’s disease ? an incurable disorder marked by tremors, movement difficulties and, sometimes, by personality changes.

The researchers at Mayo Clinic in Rochester also found that people employed as miners, production workers, metalworkers and engineers had the lowest increase in risk for Parkinson’s disease.

The study has stressed that its findings should not be interpreted to assume that education or certain occupations are harmful. The findings, the researchers said, only provide fresh clues that might help unravel the origin of the disease.

“We can’t say from this study that education and occupation are causal factors in Parkinson’s disease,” said Demetrius Maragonore, a Mayo Clinic neurologist. “I don’t think schooling or wearing a stethoscope causes brain cells to degenerate or that digging holes protects your brain cells. But these are indirect indicators of factors that may relate to brain degeneration.”

“Nobody should do anything differently because of these findings,” he added.

Neurologists in India are not surprised by these findings. Over the years, doctors have found links between personality and Parkinson’s disease. “We know that Parkinson’s disease is seen more in introverts than in extroverts,” said Uday Muthane, an associate professor at the National Institute of Mental Health and Neurosciences (Nimhans).

Parkinson’s disease is caused by a massive loss of brain cells that secrete a chemical called dopamine. While treatment involves giving dopamine substitutes, the disease typically progresses over time and is classified as incurable.

Scientists say it is possible that people with Parkinson’s disease have personalities that make them gravitate towards certain occupations or levels of education. Dopamine is the reward chemical in the brain. People with long-standing dopamine deficiency are less likely to party and more likely to sit and study, said Maragonore. “Undetected disease may shape behaviour, giving an impression that education is a risk factor.”

Psychiatrists also point to a connection between attention-demanding tasks and dopamine activity. “These are uncharted areas. So we can only speculate, but it’s conceivable that people who spend a lot of time on tasks demanding attention may be using up their dopamine pathways faster, and thus become susceptible to Parkinson’s disease,” said Sanjeev Jain, professor of psychiatry at Nimhans.

At NIMHANS, researchers are currently analysing hospital-based patients’ data to explore connections, if any, between occupation and education levels and the risk of Parkinson’s disease.