Role ofHelicobactersin Neuropsychiatric Disease: A Systematic Review in Idiopathic Parkinsonism

Interest in an aetiopathogenic role forHelicobacterin neuropsychiatric diseases started with idiopathic parkinsonism (IP), where the cardinal signs can be assessed objectively. This systematic review, using an EMBASE database search, addresses Oxford Centre for Evidence-Based Medicine based questions on the inter-relationship ofHelicobacterand IP, the benefits of eradicatingHelicobacterin IP and the outcome of not treating. The search strategy was based on Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines: 21 of 204 articles met the inclusion criteria. The results show that the assumption that any benefit ofHelicobactereradication results from improved levodopa bioavailability is unjustified. The inter-relationship betweenHelicobacterand IP is well-established.H. pylorivirulence markers (associated with autoimmunity and immune tolerance) influence the risk, severity and progression of IP. The birth cohort effect for virulence marker antibodies, seen in controls, is obliterated in IP, suggesting causality. SuccessfulH. pylorieradication in IP is disease-modifying (even in anti-parkinsonian treatment-naive patients) but not preventive. Hypokinesia regresses with eradication and overall motor severity lessens. Eradication may influence gastrointestinal microbiota adversely, unlocking the next stage in the natural history, the development of rigidity. Failed eradication worsens hypokinesia, as does the presence/persistence ofH. pyloriat molecular level only. Adequate prognostic assessment of the consequences of not treatingHelicobacter, for IP, is prevented by a short follow-up. We conclude thatHelicobacteris a pathophysiological driver of IP.