In the United States, about 50,000 to 60,000 people are newly diagnosed with Parkinson's disease each year, according to the National Parkinson Foundation. Parkinson's disease is a neurodegenerative movement disorder.
In the disorder, neurons in the substantia nigra become damaged or destroyed, affecting the production of the neurotransmitter dopamine. The loss of dopamine results in symptoms such as tremors, slowed movement, impaired balance and rigidity.
To understand what causes the damage to these dopamine-producing neurons, research has looked at possible risk factors, such as genetics. A focus has also been put on environmental factors that may contribute to the onset of the disorder.
Dr. James Bower, a neurologist from the Mayo Clinic, explained to Reuters Health that an environmental insult may be a factor in the development of Parkinson's disease in individuals who are genetically predisposed. Even in individuals who are not genetically predisposed, multiple environmental factors may result in disease development.
A new study at the University of California, Los Angeles looked at possible environmental insults that patients with Parkinson's disease may have been exposed to. The study included 357 individuals who had recently been diagnosed with Parkinson's disease and 754 controls who lived in the same area.
All the participants were asked if they had ever had a traumatic brain injury, which was characterized by a loss of consciousness for at least five minutes. The researchers also gathered the participants' addresses — home and work — to determine how close they were to pesticide sprayings since 1974.
Reuters Health reported that among the patients with Parkinson's disease, 12 percent had a history of a head injury and 47 percent had been exposed to paraquat, a type of pesticide. In comparison, 7 percent of the controls had had a head injury and 39 percent had been exposed to a pesticide.
The results of the study showed alone that these environmental insults were moderate risk factors.