Paths from Pesticides to Parkinson's

Interest in the relationship between exposure to pesticides and the risk of neurodegenerative diseases including Alzheimer's disease, amyotrophic lateral sclerosis, and Parkinson's disease (PD) is long-standing (1). PD, in particular, has been the subject of much debate in this context (2). Its symptoms typically occur later in life (at age 60 or older), with the destruction of neurons manifesting most obviously as loss of motor function. Decades of epidemiological studies have suggested that pesticide exposure is connected to the development of PD. Yet there is still much that is not clear about this relationship. The disorder likely has multiple contributing genetic and environmental factors, but how exposure to a particular chemical leads to neuronal loss and the symptoms of PD is not known. A recent meta-analysis indeed shows that epidemiologic data generally support an association between pesticides and the risk of PD (3). But what is needed is detailed information on the nature of exposure—which pesticides, at what dose, and for how long—to help design policies and practices that prevent the relevant exposures. Also needed is information on the cellular and molecular mechanisms that, over time, lead from pesticide exposure to neurodegeneration and ultimately to PD. Although many questions still linger, some recent studies appear to be advancing the field. High-quality studies of specific chemical pesticides are needed to determine the relationship between exposure and risk of Parkinson's disease. High-quality studies of specific chemical pesticides are needed to determine the relationship between exposure and risk of Parkinson's disease.