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.
Level 3 - non-randomized controlled study
Retrospective comparative cohort and case-control study using electronic health record data.
PubMed 37620120 · doi:10.1136/gutjnl-2023-329685
What was done
Using the US-based TriNetX medical record network, researchers evaluated the link between gastrointestinal conditions and Parkinson's disease (PD) via two approaches. First, in a case-control design, 24,624 patients with new-onset idiopathic PD were compared with matched negative controls (NCs), Alzheimer's disease (AD), and cerebrovascular disease (CVD) patients to identify preceding GI syndromes, appendectomy, and vagotomy. Second, in a cohort design, 18 separate GI exposure cohorts were matched to NCs and followed for 5 years to evaluate the incidence of PD, AD, and CVD.
What was found
Four GI conditions were specifically associated with PD across both designs: gastroparesis (case-control OR 4.64, cohort RR 2.43), dysphagia (OR 3.58, RR 2.27), irritable bowel syndrome (IBS) without diarrhea (OR 3.53, RR 1.17), and constipation (OR 3.32, RR 2.38; all p<0.05 or lower vs NCs). IBS with constipation showed PD specificity in the case-control analysis (OR 4.11), and intestinal pseudo-obstruction showed specificity in the cohort analysis (RR 1.84). Functional dyspepsia, IBS with diarrhea, diarrhea, and fecal incontinence were not PD-specific. Appendectomy was associated with a lower PD risk in cohort analysis (RR 0.48). Neither inflammatory bowel disease nor vagotomy was associated with PD risk.
Why it matters
This study provides large-scale epidemiological support for the Braak hypothesis by demonstrating that specific upper and lower GI motility disorders selectively precede PD rather than other neurodegenerative or cerebrovascular conditions.
Limits
As an electronic health records study, diagnoses rely on clinical coding accuracy without standardized prospective neurological or gastroenterological verification. The cohort follow-up window was limited to 5 years, which may miss longer prodromal windows. Total participant numbers across the 18 exposure cohorts are not reported in the abstract, and residual confounding from medications or lifestyle factors could not be fully controlled.
Cited by
- contradicts Individuals who have undergone a vagotomy have a significant reduction in the risk of developing Parkinson's disease.