According to new research, people who had surgery to cut the main nerve connecting the brain with the stomach, a longstanding treatment for ulcers, had a trend of a lower risk of developing Parkinson’s disease (PD). Published in the April 26 online edition of Neurology, this result adds weight to the hypothesis that PD may begin in the gut and travel to the brain.
Many scientists are investigating the idea that some of the earliest signs of PD are found in the nerve cells that line the digestive tract. For example, in recent years, scientists have found toxic clumps of alpha-synuclein protein — the hallmark of Parkinson’s — in the gut of people who later developed the disease. Additionally, early research suggests that the alpha-synuclein protein may spread through nerve cells from the intestines to the brain.
Researchers led by Bojing Liu, M.Sc., at the Karolinska Institutet in Stockholm, Sweden, studied whether two medical procedures for treating ulcers — one that surgically cuts the nerve connection from the brain to the gut and another that partially cuts it — might decrease the risk of PD. Before the advent of new drugs, these surgeries were a common therapy for treating ulcers.
Using a nationwide database of Swedish health records, the researchers found the incidence of PD in 9,430 people who had the surgery, known as vagotomy, between 1970 and 2010. Then they matched each person who had the surgery with 40 others of the same age and sex, who hadn’t had the surgery and found the incidence of PD in this control group of 377,200 individuals.
- When researchers analyzed data for people who had any type of vagotomy — partial or complete — there was no significant difference in incidence of Parkinson’s compared to people who had no surgery.
- After five years, people who had a complete severing of the nerve had a significantly lower risk of PD than those who didn’t have the surgery.
- People who had a less complete removal of the nerve’s branches did not have a lower PD risk, after five years of follow-up.
What Does It Mean?
Doctors and people with Parkinson’s have long known that the disease affects the gut. For example, constipation is an early and common symptom in Parkinson’s disease. The new study adds to accumulating evidence that may explain this connection. A previous study done in Denmark reported that after five years of follow-up, people who had undergone truncal vagotomy had a 15 percent lower Parkinson’s compared to the general population. The current study showed a similar trend but was unable to fully replicate that association.
In doing this study, scientists reasoned that, if PD starts in the gut and travels along the nerves to the brain, then cutting this connection could slow or stop PD. Their results support this idea, but the statistical strength of their results are weaker than those previously observed in Denmark.
Researchers note that even though they used a nationwide database, the incidence of people with PD and vagotomy was rare, leading to limited statistical power to analyze the data. This study provides the preliminary and indirect support to the idea that PD may spread from the gut. More studies are needed to understand the role of the gut in PD.
Liu B, Fang F, Pedersen NL, et al. (2017). Vagotomy and Parkinson Disease: A Swedish Register-Based Matched-Cohort Study. Neurology 88: 1-7