This study states that Parkinson’s disease (PD) is a neurodegenerative movement disorder that affected more than 6 million individuals worldwide in 2016.1 Although not fully understood, PD pathogenesis is a multifactorial process involving both genetic and environmental components.2 Among several postulated etiologic mechanisms, Braak’s hypothesis states that PD may be partly triggered by unknown neurotropic agents in the gastrointestinal tract, which gradually induce Lewy pathology (intraneuronal aggregation of misfolded α-synuclein, the pathogenic protein in PD) that is retrogradely transported to the brain via the vagus nerve and leads to dopaminergic neurodegeneration. This hypothesis is in line with the gastrointestinal symptoms that commonly precede the manifestation of cardinal motor signs like bradykinesia, rigidity, and resting tremor in PD patients and is supported by converging lines of evidence,5-8 which further implicate the role of gut inflammation, immune dysregulation, and gut dysbiosis in PD initiation. Microscopic colitis (MC), comprising lymphocytic colitis and collagenous colitis as two main subtypes, is a chronic intestinal inflammatory disease that has emerged as one of the most common causes of diarrhea among the elderly.12 As the mucosa of MC patients has normal appearance under colonoscopy, the diagnosis of MC requires a microscopic examination of colon biopsy.

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