Certain gut conditions may be an early sign of Parkinson’s

Researchers compared medical records of over 92,000 people in the US with Parkinson’s, other neurological conditions and those without any, to show certain gut conditions increase the risk of Parkinson’s. 

The majority of people have Parkinson’s with no known cause, known as idiopathic Parkinson’s. But researchers believe that it is a complex mix of genetic and environmental factors.

Alpha-synuclein is the troublesome protein associated with Parkinson’s that forms into sticky clumps and gradually damages dopamine-producing neurons in the brain over time. There is one theory that in some people, toxic clumps of alpha-synuclein form in the gut first and then travel to the brain, and in other people with Parkinson’s, the clumps form in the brain and then travel to the gut. The theory suggests that for some people, gastrointestinal issues such as constipation may appear before other hallmark symptoms of Parkinson’s like tremor.

Other neurological conditions, such as Alzheimer’s and cerebrovascular conditions have also been suggested to be associated with some gastrointestinal issues.

By comparing medical records of people with and without neurodegenerative conditions, the researchers aimed to determine which gastrointestinal issues may increase the risk of developing Parkinson’s. Read the full article in Gut journal here. 

What did the researchers do? 

Using a nationwide US medical network, researchers collected medical records of people from 4 different groups: 

  • People with Parkinson’s with no known cause
  • People with Alzheimer’s
  • People with cerebrovascular diseases, such as strokes and aneurysms
  • People with none of these conditions

They matched the medical records of people with Parkinson’s against each of the other conditions based on age, sex, race and ethnicity. Within their medical histories, they looked at who had any of 18 gastrointestinal issues, such as Crohn's disease, ulcerative colitis, gastroparesis (delayed gastric emptying), trouble swallowing, irritable bowel syndrome (IBS), appendectomy and diarrhoea. They did this to see whether any of the groups were more likely to have a certain gastrointestinal issue.

Then they reshuffled the groups and created 18 different groups, 1 for each gastrointestinal issue. Anyone with one of these were allocated to their relevant group and then matched up with someone who didn’t have a gut issue. Over the next 5 years, those without any gut issues were monitored to see if they developed Parkinson’s.

What were the results?

All of the gastrointestinal issues were significantly increased in people with Parkinson’s compared to those without any conditions. Some of these with the most significant increase were delayed gastric emptying, diarrhoea and constipation. Compared to people with Alzheimer’s and cerebrovascular disease, trouble swallowing, IBS with constipation and IBS without diarrhoea were all issues that had a significantly higher presence in people with Parkinson’s.

After following the groups without any gut issues for 5 years, the results suggested that those with trouble swallowing, delayed stomach emptying, IBS without diarrhoea, a dilated bowel or constipation had a higher risk of developing Parkinson’s in comparison to Alzheimer’s and cerebrovascular disease. This suggests that a number of the gut issues are linked more closely to Parkinson’s than other similar conditions. 

How could these results help with our understanding of Parkinson’s?

This study adds to our knowledge on the complex relationship between gut issues and Parkinson’s. Further research is now needed to understand why these gastrointestinal issues are linked to a higher risk of developing Parkinson’s, and whether treating these gut issues could potentially prevent Parkinson’s from developing.

Claire Bale, Associate Director of Research at Parkinson’s UK said: 
"The findings add further weight to the growing evidence that problems like constipation, difficulty swallowing and delayed stomach emptying may be early warning signs of Parkinson's.

"Understanding how and why gut issues appear in the early stages of Parkinson's could open up opportunities for early detection and treatment approaches that target the gut to improve symptoms and even slow or stop the progression of the condition."