Vibrations Both Increase and Reduce the Risk of Parkinson's Disease

From detailed occupational histories and published measurements, metrics of occupational WBV exposure were constructed and tested for associations with PD, using logistic regression and adjusting for age and sex first, and then also for smoking and history of head injury.

The researchers found that those exposed to high-intensity vibrations--for example, by driving snowmobiles, military tanks, or high-speed boats--had a consistently higher risk of developing PD than people whose jobs involved lower-intensity vibrations, such as operating road vehicles. The results were significant for intermediate intensities, when exposures were restricted to the 10 years or more prior to diagnosis. The researchers stressed that the elevated risk fell short of the statistical significance typically used to establish a correlation, but was strong and consistent enough to suggest an avenue for further research.

One of the possible mechanisms of an inverse relation between low levels of WBV exposure and Parkinson's disease could include direct protective effects or correlation with other protective effects such as exercise. Higher intensities of WBV could result in micro-injury, leading to vascular or inflammatory pathology in susceptible neurons, as suggested by previous studies that found that mechanical stress producing head injury is associated with PD. The study was published early online on July 12, 2012, in the American Journal of Epidemiology.

“There are no cures or prevention programs for Parkinson's, in part because we still don't understand what triggers it in some people and not others,” said lead author Anne Harris, PhD, of the UBC Pacific Parkinson's Research Center. “This kind of painstaking epidemiological detective work is crucial in identifying the mechanisms that might be at work, allowing the development of effective prevention strategies.”

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