Blood profile holds clues to role of infection in a premonitory state for idiopathic parkinsonism and of gastrointestinal infection in established disease
Authors: Charlett André , Dobbs R John , Dobbs Sylvia M , Weller Clive , Ibrahim Mohammad AA , Dew Tracy , Sherwood Roy , Oxlade Norman L , Plant J Malcolm , Bowthorpe James , Lawson Andrew J , Curry Alan , Peterson Dale W , Bjarnason Ingvar T 
Published: November 2009

The two-stage neuroinflammatory process, containment and progression, proposed to underlie neurodegeneration may predicate on systemic inflammation arising from the gastrointestinal tract.Helicobacterinfection has been described as one switch in the pathogenic-circuitry of idiopathic parkinsonism (IP): eradication modifies disease progression and marked deterioration accompanies eradication-failure. Moreover, serumHelicobacter-antibody-profile predicts presence, severity and progression of IP. Slow gastrointestinal-transit precedes IP-diagnosis and becomes increasingly-apparent after, predisposing to small-intestinal bacterial-overgrowth (SIBO). Although IP is well-described as a systemic illness with a long prodrome, there has been no comprehensive overview of the blood profile. Here, it is examined in relation toHelicobacterstatus and lactulose-hydrogen-breath-testing for SIBO.

A robust finding of reduced lymphocyte count in 126 IP-probands and 79 spouses (without clinically-definite IP), compared with that in 381 controls (p < 0.001 in each case), was not explained byHelicobacter-status or breath-hydrogen. This complements a previous report that spouses were 'down-the-pathway' to 'clinically-definite' disease. In 205 other controls without clinically-definite IP, there were strong associations between sporadic cardinal features and immunoglobulin class concentration, not explained byHelicobacter-status. Premonitory states for idiopathic parkinsonism associated with relative lymphopenia, higher serum immunoglobulin concentrations and evidence of enteric-nervous-system damage may prove viral in origin.

Although only 8% of the above 79 spouses were urea-breath-test-positive forHelicobacter, all 8 spouses with clinically-definite IP were (p < 0.0001). Transmission of a 'primer' to aHelicobacter-colonised recipient might result in progression to the diagnostic threshold.

Twenty-five percent of the 126 probands were seropositive for anti-nuclear autoantibody. In 20 probands, monitored before and serially after anti-Helicobactertherapy, seropositivity marked a severe hypokinetic response (p = 0.03). It may alert to continuing infection, even at low-density. Hyperhomocysteinemia is a risk factor for dementia and depression. Serum homocysteine exceeded the target in 43% of the 126 IP-probands. It was partially explained by serum B12 (12% variance, p < 0.001), but not byHelicobacter-status (gastric-atrophy uncommon in IP) or levodopa treatment. Immune-inflammatory activation increases homocysteine production. Since an estimated 60% of probands are hydrogen-breath-test positive, SIBO, with its increased bacterial utilisation of B12, is a likely cause. Thus, two prognostic indicators in established IP fit with involvement ofHelicobacterand SIBO.