The recent study published in the online issue of Neurology®, the medical journal of the American Academy of Neurology shows the light to a new research on the association of Parkinson’s disease with the gut.
The team from United States and Sweden made a study using data from Swedish nationwide registers of people who had resection surgery, removing the main trunk or branches of the vagus nerve. The surgery, called vagotomy, is used for people with ulcers. Even though the figures of Parkinson’s disease on people who had a vagotomy over a 40-year period with that of general population had no significant difference, the analysis of results for the two different types of vagotomy surgery found some variation.
The vagus nerve extends from the brain stem to the abdomen and controls unconscious body processes like heart rate and food digestion. They found that people who had a truncal vagotomy at least five years earlier were less likely to develop Parkinson’s disease than those who had not had the surgery and had been followed for at least five years. In a truncal vagotomy, the nerve trunk is fully resected. In a selective vagotomy, only some branches of the nerve are resected.
A total of 19 people who had truncal vagotomy at least five years earlier developed the disease, or 0.78 percent, compared to 3,932 people who had no surgery and had been followed for at least five years, at 1.15 percent. By contrast, 60 people who had selective vagotomy five years earlier developed Parkinson’s disease, or 1.08 percent.
Gastrointestinal symptoms, in particular constipation, are among the most common nonmotor symptoms of Parkinson disease (PD). Braak and the team hypothesized that in PD the Lewy pathology may start in peripheral nerves such as the enteric nervous system and later spread to the CNS through the vagus nerve via prion-like mechanisms. In support of this, recent pathologic studies found Lewy-type deposition in the gut of individuals with prodromal PD.
In addition, other studies have shown that people who will later develop Parkinson’s disease have a protein believed to play a key role in Parkinson’s disease in their gut. The theory is that these proteins can fold in the wrong way and spread that mistake from cell to cell.
“Although overall vagotomy was not associated the risk of PD, we found suggestive evidence for a potential protective effect of truncal, but not selective, vagotomy against PD development”, responded the team
“Much more research is needed to test this theory and to help us understand the role this may play in the development of Parkinson’s,” Liu said. Additionally, since Parkinson’s is a syndrome, there may be multiple causes and pathways.
One limitation that the team face is small numbers in certain subgroups and also, the researchers could not control all the potential factors that could affect the risk of Parkinson’s disease, such as smoking, coffee drinking or genetics.