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Helicobacter Hypothesis for Idiopathic Parkinsonism: Before and Beyond.

R John Dobbs, Sylvia M Dobbs, Clive Weller, André Charlett, Ingvar T Bjarnason et al. Helicobacter 2008;13:309-22.

Abstract: We challenge the concept of idiopathic parkinsonism (IP) as inevitably-progressive neurodegeneration, proposing a natural history of sequential microbial insults with predisposing host response.

Proof-of-principle that infection can contribute to IP was provided by case-studies and a placebo-controlled efficacy study of Helicobacter eradication. “Malignant” IP appears converted to “benign”, but marked deterioration accompanies failure. Similar benefit on brady/hypokinesia from eradicating “low-density” infection favours autoimmunity. Although a minority of UK probands are urea-breath-test positive for Helicobacter, the predicted probability of having the parkinsonian label depends on the serum H. pylori antibody profile, with clinically-relevant gradients between this “discriminant-index” and disease-burden and progression.

In IP, H. pylori antibodies discriminate for persistently abnormal bowel function, and specific abnormal duodenal enterocyte mitochondrial morphology is described in relation to H. pylori infection. Slow intestinal transit manifests as constipation from the prodrome. Diarrhoea may flag secondary small-intestinal bacterial overgrowth. This, coupled with genetically determined intense inflammatory response, might explain evolution from brady/hypokinetic to rigidity-predominant parkinsonism.