Digestive problems may be an early sign of Parkinson's disease
A new study suggests that digestive problems, including constipation, difficulty swallowing, and irritable bowel syndrome, may be an early warning sign of Parkinson's disease in some people.
The findings, published in the journal "Gut", add more evidence to the idea that brain and gut health are closely linked.
The researchers say that understanding the cause of digestive problems, could allow for early treatment of Parkinson's disease.
- What is Parkinson's disease?
People with Parkinson's disease do not have enough of the chemical dopamine in their brains due to damage to some of the nerve cells that produce it.
This causes symptoms that include involuntary shaking or tremors, slow and reduced movements, and muscle stiffness.
Although there is currently no cure, there are treatments available that help to reduce the main symptoms and maintain quality of life as much as possible.
Early detection of the disease - before neurological symptoms appear and significant damage to brain cells occurs - could make a big difference.
For the study, researchers analyzed American medical records of 24,624 people with Parkinson's disease, and compared them to:
19,046 people with Alzheimer's disease.
23,942 people with a brain hemorrhage or stroke (cerebrovascular disease).
24,624 people with healthy brains.
- What they wanted to know was:
How often did patients with Parkinson's disease have any previous digestive problems in the six years prior to their diagnosis of the brain disorder?
Do people with digestive problems have a higher chance of developing Parkinson's disease?
The answer to both questions was "yes", based on five years of data collected.
Specifically, four conditions related to the digestive system - constipation, difficulty swallowing, slowing of the movement of food to the small intestine (gastroparesis - a condition that affects the natural, involuntary movement of the muscles in your stomach), and irritable bowel syndrome - were linked to an increased risk of Parkinson's disease.
However, it seems that appendectomy may be protective, which is something other scientists have confirmed before.
The researchers stress that not everyone who experiences digestive problems will develop Parkinson's disease, but it appears that there is some kind of link between gut health and the brain.
- The gut-brain axis
The gut contains millions of nerve cells that communicate with the brain. Experts say it is possible that treatments that help one system could also help the other system, or that disease in one area will impact other areas.
Claire Bale from Parkinson's UK said the findings "add further weight" to the hypothesis that digestive problems may be an early sign of the disease.
Professor Kim Barrett, from the University of California, Davis, said more studies are needed to understand whether the link is something that could be used by doctors to help patients.
She adds that "it is still possible that both gut conditions and Parkinson's disease are independently linked to a third, as yet unknown, risk factor. The study in question cannot definitively establish cause and effect, however, the findings may have clinical significance and certainly should stimulate further studies."
Dr Tim Bartels, from the Alzheimer's Research Institute, at University College London, explains that this work strongly establishes that the gut may be a "prime target" for the search for biomarkers for Parkinson's disease, measurable physical changes that could be an early warning sign.
He added that the ability to predict Parkinson's disease earlier would be "extremely valuable and more effective for finding early treatment."