Physicians and individuals with 9 or more years of education are at an increased risk of developing Parkinson's disease, according to a study by Dr. Roberta Frigerio of the Mayo Clinic in Rochester, Minn., and her colleagues.
Dr. Frigerio conducted the research at Mayo while on leave from the University of Milano-Bicocca, Monza, Italy.
Individuals such as construction and extractive workers, production workers, metal workers, and engineers who have more physically demanding jobs are at a reduced risk for the disease, the researchers found (Neurology 2005; 65:1575–83).
The researchers examined the education levels and occupations of 202 individuals in Olmsted County, Minn., who developed Parkinson's disease from 1976 through 1995.
Each case was matched by age and sex to a general population control who was free of Parkinson's disease and living in the same county. Of those individuals, they were able to obtain medical records for 196 cases and 196 controls. In addition, they obtained data from telephone interviews available for 149 cases and 129 controls.
But the findings should not be a cause for alarm among physicians or those with higher levels of education, said Dr. Demetrius Maraganore, a professor of neurology at the Mayo Clinic and one of the study authors, in an interview.
The number of physicians in the study was small and therefore the effect size is unstable.
“Parkinson's disease is a thousand-piece puzzle,” Dr. Maraganore said.
More research is needed to figure out what these findings mean. For example, the findings could mean that being a physician is an indirect marker for other environmental factors.
Or it could be that being a physician or having more education are not risk factors at all, he said.
Instead, additional years of schooling and becoming a physician could be early manifestations of the disease, which affects personality and behavior.
A deficiency of dopamine could shape personality in a way that makes a person more inclined to sit at a desk and study, he said.