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
E1,2, Henderson VW1,3,4, Szépligeti S1, Stokholm MG5, Klug TE6, Sørensen HT1,3, Borghammer 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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