Parkinson's disease has long been considered a disease of the brain, but research out Wednesday found it may start in the gut - specifically in the appendix, a tiny organ near the large intestine. Using health registries in Sweden and the United States, researchers found that those who had their appendix removed in early adulthood generally saw their risk of developing the incurable neurodegenerative disorder cut by 19 percent, said the study in the journal Science Translational Medicine.
In rural areas of Sweden, where people may be more exposed to pesticides - which have been shown to play a role in Parkinson's - the effect was even greater: a 25 percent lower risk. "Among people who did develop Parkinson's disease, we found that the age of onset was delayed by an appendectomy on average by 3.6 years," study author Viviane Labrie, assistant professor at Van Andel Research Institute in Michigan, said during a conference call with reporters.
"Our studies suggest that the appendix might be a tissue site that plays a role in the early events or initiation of Parkinson's disease." Parkinson's affects millions of people worldwide. Some of the celebrities afflicted include actors Michael J. Fox and Alan Alda, singer Neil Diamond and the late boxer Muhammad Ali.
Often, the appendix is considered a useless organ. But researchers say it is a storage site for gut bacteria, is linked to immune response, and appears to be a gathering place for a key protein implicated in Parkinson's, known as alpha-synuclein.
Knowing that people with Parkinson's also suffer from gastrointestinal disorders like constipation at least 10 years before the disease's better known symptoms like tremors, stiffness, and poor balance surface, researchers decided to take a closer look at the appendix and its potential role. They found that nearly everyone has signs of clumped up alpha-synuclein present in their appendix.
But not everyone goes on to develop Parkinson's, for reasons that still aren't well understood. "We think that in rare events, if it (alpha-synuclein) were to escape the appendix and enter the brain, this could lead to Parkinson's disease," Labrie told reporters. In fact, "alpha-synuclein is a protein that doesn't like to stay put," she added. "It's able to move from neuron to neuron."