Small intestinal bacterial overgrowth (SIBO) is defined as an increased bacterial density greater than 10 5 colony-forming units/mL and/or abnormal types of bacteria in the small intestinal tract. Recent research has shown changes in the intestinal microbiota of PD patients, which is associated with the clinical phenotype of PD. PD affects the nerves of the entire gastrointestinal (GI) tract, and most PD patients experience abnormal gastrointestinal motility and delayed gastric emptying. In addition to the above motor-related manifestations, PD patients often have nonmotor symptoms, such as anosmia, sleep disorders, depression and constipation. The symptoms are the classic triad of Parkinsonian motor features: bradykinesia, resting tremor and rigidity. The pathogenesis of PD remains unclear it is generally believed that it may be related to the environment, ageing, heredity and other factors. The neuropathologic changes of PD include abnormal accumulation of alpha-synuclein and degenerative necrosis of dopaminergic neurons in the substantia nigra. Parkinson’s disease (PD) is the second most prevalent neurodegenerative disease after Alzheimer's disease (AD) worldwide. These relationships significantly differed based on diagnostic test and geographic area. In conclusion, our meta-analysis found a strong association between SIBO and PD with approximately half of PD patients testing positive for SIBO. We did not identify an obvious predictor of SIBO in PD patients. The pooled OR of SIBO in PD patients compared with healthy controls was 5.22 (95% CI 3.33–8.19, p < 0.00001). The prevalence of SIBO was 52% (95% CI 40–64) among patients from Western countries and 33% (95% CI 22–43) among patients from Eastern countries.
Subgroup analyses showed that the prevalence of SIBO was greater in studies including patients diagnosed using the lactulose hydrogen breath test (LBT) (51%, 95% CI 37–65) than in those including patients diagnosed using the glucose hydrogen breath test (GBT) (35%, 95% CI 20–50), and the prevalence of SIBO in PD was highest (55%, 95% CI 38–72) in patients diagnosed by the LBT and GBT. Egger’s test indicated no publication bias (p = 0.0657). A random-effects model was applied given the heterogeneity (I 2 = 83%) detected among the studies. The pooled prevalence of SIBO in patients with PD was 46% (95% CI 36–56). ResultsĮleven studies with 973 participants met the inclusion criteria. Egger’s test was performed to assess publication bias. We calculated the pooled prevalence of SIBO in all individuals with PD and compared the prevalence of SIBO between the two groups to calculate an odds ratio (OR) and 95% confidence interval (CI). Studies were screened, and relevant data were extracted and analysed. MethodsĪ comprehensive literature search of the PubMed, Cochrane Library and EMBASE databases was performed to identify studies correlating SIBO with PD.
We conducted this comprehensive systematic review and meta-analysis to determine the association between SIBO and PD. The prevalence of small intestinal bacterial overgrowth (SIBO) in PD patients is high.