Environmental Factors

Image from NIEHS, NIH

Exposure to environmental factors can strongly influence risk of PD. Environmental factors that have been identified with varying degrees of association include heavy metals and other toxins, biological pathogens, recreational and pharmaceutical drug use, dietary factors, and medical history. Certain occupations have also been identified as risk factors, presumably by increasing an individual’s exposure to an environmental risk factor (Kasten et. al., 2007; Elbaz and Moisan, 2008).

Epidemiological studies of environmental risk factors for PD are complicated by a number of experimental limitations. These include the inherent difficulty of classifying people with PD based on purely clinical diagnostic criteria, as well as the fact that poor understanding of the etiology of PD leads to uncertainty about the window of exposure that may be critical for a specific environmental factor to have its adverse effect (Kasten et al., 2007).

The exact role played by environmental factors in causing classic idiopathic PD is unclear, and some have argued that no environmental cause of idiopathic PD has yet been definitively identified (Hardy et al., 2006).