Friday, December 8, 2017

Out of the mouths of babes and sucklings: gut to PD

reposted from



Out of the mouths of babes and sucklings

There is an ongoing debate about where Parkinson’s starts. The most accepted hypothesis of Braak and colleagues suggests that it starts outside the brian, either in the olfactory (smelling) nerve, or potentially in the gut. Some evidence suggested that people who had had surgery to cut the nerve to their stomach to treat stomach ulcers were at lower risk of Parkinson’s, which added weight to the theory that Parkinson’s might ‘ascend’ through the nerves of the gut to the brain. This fits nicely with the theory that changes in the microbiome (the overall ecosystem of bacteria and other microorganisms) in the gut plays a part in Parkinson’s. However, this finding has been disputed by other studies.

A report published this month, continues the story elsewhere in the digestive tract. Using the highly reliable public health records of the Danish health and civil registration scheme, they tried to find a relationship between having a tonsillectomy and future risk of Parkinson’s. They examined ther records of over a million people, including 195,000 who’d had tonsillectomy, primarily in childhood. They found 100 people who developed Parkinson’s from the tonsillectomy group at a rate of 0.31 (true figure in the region of 0.22-0.34) cases of Parkinson’s per 100,000 person-years, and 568 cases of Parkinson’s in the comparison group at 0.27 (true figure in the region of 0.29-0.34) cases of Parkinson’s per 100,000 person-years. There was no significant difference between the two groups. Therefore, there is no evidence of any effect of tonsillectomy on the risk of developing Parkinson’s.

This is an important negative finding, and the editor of Movement Disorders should be congratulated on publishing it. It is notoriously difficult to publish ‘negative’ studies, as they rarely make headlines in the broadsheets (when was the last time you read that X had no effect on Y, compared to the last story you read claiming that your favourite food put you at risk of …) Although they found no evidence of an effect, that still isn’t quite the same of finding evidence of no effect; and so the debate rages on.

RNR


Tonsillectomy and Risk of Parkinson’s Disease: A Danish Nationwide Population-Based Study
Svensson E1,2Henderson VW1,3,4Szépligeti S1Stokholm MG5Klug TE6Sørensen HT1,3Borghammer P5.


ABSTRACT
Background: We hypothesized that tonsillectomy modifies the risk of PD.
Objectives: To test the hypothesis in a nationwide population-based cohort study.
Methods: We used Danish medical registries to construct a cohort of all patients in Denmark with an operation code of tonsillectomy 1980-2010 (n = 195,169) and a matched age and sex general population comparison cohort (n = 975,845). Patients were followed until PD diagnosis, death, censoring, or end of follow-up 30 November 2013. Using Cox regression, we computed hazard ratios for PD and corresponding 95% confidence intervals, adjusting for age and sex by study design, and potential confounders.
Results: We identified 100 and 568 patients diagnosed with PD among the tonsillectomy and general population comparison cohort, respectively, finding similar risks of PD (adjusted hazard ratio = 0.95 [95% confidence interval: 0.76-1.19]; for > 20 years' follow-up (adjusted hazard ratio = 0.96 [95% confidence interval: 0.64-1.41]).
Conclusion: Tonsillectomy is not associated with risk of PD, especially early-onset PD. © 2017 International Parkinson and Movement Disorder Society


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