Parkinson's disease (PD) and Alzheimer's disease (AD) are the most common neurodegenerative disorders, with an overall global incidence of 40 million. Many studies have revealed the association of intestinal disorders and bacterial infections with PD, but few studies have found such a relationship with AD. In this meta-analysis, related articles published up to September 2018 were searched in PubMed. Of the 2121 related articles screened initially, 56 were found to be eligible. Data on the risks of PD and AD due to five intestinal disorders and infection with Helicobacter pylori, as a representative intestinal microbe, were obtained, and a fixed- or random-effects model was used to pool the odds ratios (ORs) with 95% confidence interval (CIs) from individual studies. The combined OR for all types of intestinal disorders with an increased risk of PD was 3.36 (95% CI: 2.70-4.17). The ORs for each category were as follows: constipation, 4.05 (95% CI, 3.24-5.06); inflammatory bowel disease (IBD), 1.16 (95% CI, 0.89-1.52); irritable bowel syndrome (IBS), 1.75 (95% CI, 0.55-5.56); small intestinal bacterial overgrowth, 5.15 (95% CI, 3.33-7.96); and diarrhea, 1.27 (95% CI, 0.28-5.75). The combined OR of all types of intestinal disorders with an increased risk of AD was 1.52 (95% CI, 1.09-2.13). The ORs for IBS and IBD were 1.42 (95% CI, 1.02-1.99) and 2.40 (95% CI, 1.00-5.76), respectively. The risk estimates of H. pylori infection in PD and AD patients were as follows: OR, 1.65 (95% CI, 1.43-1.91) and OR, 1.40 (95% CI, 1.12-1.76), respectively. These findings suggest that PD and AD are significantly associated with intestinal disorders. The negative roles of H. pylori in the development of PD or AD should be evaluated to shed new light on the diagnosis and treatment of PD and AD. National governments should periodically inspect the intestinal condition of residents and extend health plans to improve intestinal health to prevent potential neurological disorders.

中文翻译：

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肠道疾病与帕金森氏病和阿尔茨海默氏病的关联：系统评价和荟萃分析。

帕金森氏病（PD）和阿尔茨海默氏病（AD）是最常见的神经退行性疾病，全球总发病率为4000万。许多研究揭示了肠道疾病和细菌感染与PD的关系，但很少有研究发现与AD有这种关系。在这项荟萃分析中，在PubMed中搜索了截至2018年9月发表的相关文章。最初筛选的2121条相关文章中，有56条符合条件。获得了有关五种肠道疾病和幽门螺杆菌（作为代表性的肠道微生物）感染导致的PD和AD风险的数据，并使用固定效应或随机效应模型汇总了95％的优势比（OR）个别研究的置信区间（CIs）。发生PD风险增加的所有类型肠道疾病的合并OR为3.36（95％CI：2.70-4.17）。每个类别的OR如下：便秘4.05（95％CI，3.24-5.06）；炎症性肠病（IBD），1.16（95％CI，0.89-1.52）；肠易激综合征（IBS），1.75（95％CI，0.55-5.56）; 小肠细菌过度生长，5.15（95％CI，3.33-7.96）; 和腹泻为1.27（95％CI，0.28-5.75）。患有AD风险增加的所有类型肠道疾病的合并OR为1.52（95％CI，1.09-2.13）。IBS和IBD的OR分别为1.42（95％CI，1.02-1.99）和2.40（95％CI，1.00-5.76）。PD和AD患者中幽门螺杆菌感染的风险评估如下：OR分别为1.65（95％CI，1.43-1.91）和OR，1.40（95％CI，1.12-1.76）。这些发现表明PD和AD与肠道疾病显着相关。应评估幽门螺杆菌在PD或AD发生中的负面作用，从而为PD和AD的诊断和治疗提供新的思路。各国政府应定期检查居民的肠道状况，并扩展健康计划以改善肠道健康，以预防潜在的神经系统疾病。