This is a drawing of a man holding his belly.
Both analyses indicated that 4 gut conditions were associated with a higher risk of a Parkinson’s disease diagnosis. Credit: Neuroscience News

Gut Instincts: Can Digestive Issues Predict Parkinson’s Onset?

Summary: New research posits that particular gastrointestinal issues may be precursors to Parkinson’s disease.

Utilizing a vast US medical record network, the study contrasted people diagnosed with Parkinson’s against those with Alzheimer’s, cerebrovascular disease, or none of these conditions.

The outcome revealed four gut problems that hinted at a heightened Parkinson’s risk: gastroparesis, dysphagia, constipation, and non-diarrheal IBS.

However, appendix removal showed a potentially protective effect, sparking curiosity about its influence in the disease’s genesis.

Key Facts:

  1. Four specific gut conditions—gastroparesis, dysphagia, constipation, and IBS without diarrhea—elevate the risk of Parkinson’s disease diagnosis.
  2. While appendix removal appears to lower Parkinson’s risk, its exact role in the disease remains uncertain.
  3. The study is observational and cannot define causation, but it underlines the importance of monitoring gastrointestinal issues in individuals more susceptible to Parkinson’s.

Source: BMJ

Certain gut problems, such as constipation, difficulty swallowing, and irritable bowel syndrome (IBS), may be early warning signs of the neurological condition Parkinson’s disease, suggests research published online in the journal Gut.

Gastrointestinal symptoms are thought to precede the development of cerebrovascular disease, such as stroke or a brain aneurysm, or Alzheimer’s disease, and it has been suggested (Braak’s hypothesis) that gut conditions may precede the development of Parkinson’s disease too.

Credit: Neuroscience News

To test this hypothesis, the researchers used data from a US nationwide medical record network (TriNetX) to compare 24, 624 people who had been diagnosed with Parkinson’s disease of unknown cause with those who had been diagnosed with other neurological conditions—Alzheimer’s disease (19,046) or cerebrovascular disease (23,942)—or with none of these (24,624; comparison group). 

Those with Parkinson’s disease were matched with people in the other groups for age, sex, race and ethnicity, and length of diagnosis to compare the frequency of gut conditions included in their electronic health record for an average of 6 years before their Parkinson’s disease diagnosis.

The researchers then tested the same hypothesis, but in a different way, by dividing all the adults in the network who had been diagnosed with any of 18 gut conditions into separate groups—one for each condition of interest. 

People in these groups were matched with people without the particular gut condition and monitored via their medical records for 5 years to see how many of them developed Parkinson’s disease or other neurological disorders. 

Both analyses indicated that 4 gut conditions were associated with a higher risk of a Parkinson’s disease diagnosis. 

Specifically, gastroparesis (delayed stomach emptying), dysphagia (difficulty swallowing), and constipation were all associated with a more than doubling in risk of Parkinson’s disease in the 5 years preceding the diagnosis, while IBS without diarrhea was associated with a 17% higher risk. 

Appendix removal, however, seemed to be protective, prompting questions about its potential role in the disease processes leading to Parkinson’s disease, say the researchers. 

Neither inflammatory bowel disease nor vagotomy (removal of all or part of the vagus nerve to treat peptic ulcer) were associated with a heightened risk.

Some other gut issues, including functional dyspepsia (burning sensation or fullness of the stomach with no obvious cause); IBS with diarrhea; and diarrhea plus fecal incontinence, were also more prevalent among people who developed Parkinson’s disease. 

But these conditions were also more prevalent before the onset of Alzheimer’s disease or cerebrovascular disease.

This is an observational study, and as such, can’t establish cause. The researchers also highlight several limitations to their findings, including that the monitoring period was relatively short and that the diagnostic information captured in electronic health records might have been incomplete.

Nevertheless, they conclude: “This study is the first to establish substantial observational evidence that the clinical diagnosis of not only constipation, but also dysphagia, gastroparesis and irritable bowel syndrome without diarrhea might specifically predict the development of Parkinson’s disease.”

They add: “These findings warrant alertness for [gastrointestinal] syndromes in patients at higher risk for Parkinson’s disease and highlight the need for further investigation of [gastrointestinal] precedents in Alzheimer’s disease and cerebrovascular disease.”

About this Parkinson’s disease research news

Author: Caroline White
Source: BMJ
Contact: Caroline White – BMJ
Image: The image is credited to Neuroscience News

Original Research: Open access.
Gastrointestinal syndromes preceding a diagnosis of Parkinson’s disease: testing Braak’s hypothesis using a nationwide database for comparison with Alzheimer’s disease and cerebrovascular diseases” by Pankaj Jay Pasricha et al. GUT


Gastrointestinal syndromes preceding a diagnosis of Parkinson’s disease: testing Braak’s hypothesis using a nationwide database for comparison with Alzheimer’s disease and cerebrovascular diseases


Braak’s hypothesis states that Parkinson’s disease (PD) originates in the gastrointestinal (GI) tract, and similar associations have been established for Alzheimer’s disease (AD) and cerebrovascular diseases (CVD). We aimed to determine the incidence of GI syndromes and interventions preceding PD compared with negative controls (NCs), AD and CVD.


We performed a combined case-control and cohort study using TriNetX, a US based nationwide medical record network. Firstly, we compared subjects with new onset idiopathic PD with matched NCs and patients with contemporary diagnoses of AD and CVD, to investigate preceding GI syndromes, appendectomy and vagotomy. Secondly, we compared cohorts with these exposures to matched NCs for the development of PD, AD and CVD within 5 years.


We identified 24 624 PD patients in the case-control analysis and matched 18 cohorts with each exposure to their NCs. Gastroparesis, dysphagia, irritable bowel syndrome (IBS) without diarrhoea and constipation showed specific associations with PD (vs NCs, AD and CVD) in both the case-control (odds ratios (ORs) vs NCs 4.64, 3.58, 3.53 and 3.32, respectively, all p<0.0001) and cohort analyses (relative risks (RRs) vs NCs 2.43, 2.27, 1.17 and 2.38, respectively, all p<0.05). While functional dyspepsia, IBS with diarrhoea, diarrhoea and faecal incontinence were not PD specific, IBS with constipation and intestinal pseudo-obstruction showed PD specificity in the case-control (OR 4.11) and cohort analysis (RR 1.84), respectively. Appendectomy decreased the risk of PD in the cohort analysis (RR 0.48). Neither inflammatory bowel disease nor vagotomy were associated with PD.


Dysphagia, gastroparesis, IBS without diarrhoea and constipation might specifically predict Parkinson’s disease.

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