Do gut problems increase risk of Parkinson's disease? New study suggests yes

Parkinson's disease is a neurological disorder that affects the nervous system. Researchers have long thought that the disease begins in the brain, but a growing body of research is showing that in some patients, it may actually begin in the gut.

New study led by researchers at Beth Israel Deaconess Medical Center
Found It was found that people with a history of upper gastrointestinal injuries, such as ulcers, had a 76% higher risk of developing Parkinson's disease compared to people without such a history.

The study's lead author, Dr. Tricia Pasricha, of GBH All things considered Host Arun Rath explains the connection between Parkinson's disease and gut health. Below is a lightly edited transcript.

Arun Rath: The list of symptoms traditionally associated with Parkinson's disease includes tremors and stiffness of movement. [don’t seem] It doesn't seem to have anything to do with the digestive tract. When did researchers first suspect there might be a link between the digestive tract and Parkinson's?

Dr. Tricia Pasricha: Yes, that's a great question. The idea that Parkinson's disease might originate in the gut is a hypothesis that's been around for at least 20 years.

But what's interesting is, when you talk to people with Parkinson's, many of them [are] Symptoms include tremors and difficulty walking. [about their gut health]You might say, “Well, I've had constipation for years before I had motor symptoms,” or, “Yes, I started to have mild nausea, and I don't know why, but it's been going on for years.”

As more and more people experience this, researchers like me and others in the field are beginning to say, “So why?” Why do these people tend to present with symptoms like constipation, irritable bowel syndrome, nausea, and swallowing problems — all those gastrointestinal symptoms — years, or even decades, before other commonly associated symptoms, like tremors, begin?

Russ: Looking back from there – from 20 years ago to your current research – where did it lead?

Pasricha: Yes. So, a little over 20 years ago, this hypothesis was put forward.
Braak's hypothesisbased on researchers who were the first to describe this in the literature, the idea is that there's some trigger happening outside the brain, also in the gut, that causes the protein alpha-synuclein to misfold, which we know is involved in the death of dopaminergic neurons in the brain.

In fact, we have some kind of trigger [causes] The protein probably first gets misfolded in the gut, and when that protein gets misfolded, it travels from the gut up the vagus nerve to the brain, eventually causing the classic symptoms of tremors, difficulty walking, and stiffness.

Russ: Could that lead to a way to understand the onset of Parkinson's disease earlier than normal?

Pasricha: So that's the hope. So most of these symptoms, the GI symptoms, often begin much earlier than the motor symptoms. And the idea for gastroenterologists in this field, experts like myself, is to pinpoint as precisely as possible what the triggers are in the gut.

That was the trigger for this study: can we intervene early in the pathology that occurs in the gut before it reaches the brain? Our work is based on this hypothesis, which has been described in the literature. [and was] It was mentioned only once in a paper from the 1960s, where a doctor stated: [their] People with Parkinson's disease are more likely than others to develop duodenal and gastric ulcers, but the reasons why haven't been fully understood, and the medical literature has been silent on the issue for decades.

But then, after I became a neurogastroenterologist and had been in practice for several years, I too began to notice that some of my Parkinson's patients tended to complain of not only stomach ulcers, but also erosions and intestinal problems years before they were diagnosed.

That's what prompted us to do this study in a large patient population, to actually look at what happens to people who have damage to the mucosa, the lining, of the intestine. Are these people actually at higher risk for developing Parkinson's disease? And indeed that's what we found.

Russ: Parkinson's is, of course, a horrible disease. It's progressive and there is no cure. If we can understand the triggers you describe, is it possible that we might one day be able to stop Parkinson's before it starts?

Pasricha: Well, that's the hope, and certainly, that's what we hope to achieve with this research one day. You're right, right now we don't have the drugs that can stop the progression in the way that we would like.

But the hope is that if we can confirm that, at least in some patients, the disease starts somewhere in the gut, we can identify what that pathway is and target it with some kind of treatment. We're not there yet.

Many people, [reading about] The researchers in this study are asking, “If you have peptic ulcers, what can you do to reduce your risk of Parkinson's?” We're not yet at the point where we can say, “Here's how to stop the progression to full-blown Parkinson's.” But what I can tell people with confidence is that certain steps to promote gut health and help the gut lining will only benefit you, regardless of your risk for Parkinson's.

Reducing NSAID use [nonsteroidal anti-inflammatory drugs] Taking ibuprofen, cutting back on alcohol, and reducing stress where possible can all help your gastrointestinal lining and your overall health.

Russ: The number of Parkinson's disease patients is increasing rapidly. I hadn't noticed it, but apparently it's happening worldwide.
Doubled Do we know the reasons for this sudden increase over the past 25 years, and do you think this new study will shed light on why?

Pasricha: That's a great question. Over the past 25 years, the number of cases has actually doubled, leading some to call it a “Parkinson's pandemic.”

Now, the biggest risk factor is age. We're an aging population. There is certainly a genetic component, but most people don't know their genetic risk. So we start to ask, what are the environmental factors that have changed over the last few years, over the last few decades that are contributing to stomach cancer, and what is it about those environmental factors that is influencing stomach cancer?

One of the environmental factors that we're very concerned about is, of course, food. Our diet today is very different from the diet of people in the 1950s. It's very different from the diet of people in the 1850s. We process our food in many ways. We process our food heavily. We eat foods that are high in fats.

These substances, even in low concentrations, damage the intestinal wall, and we don't yet know exactly what role they play, but it's certainly one of the factors we're investigating.

Russ: We've covered a lot of areas and big questions, but I want to ask one other big question: Does this have any implications for research into the origins of other neurodegenerative diseases, such as Alzheimer's?

Pasricha: That's a great question and an important question. Alzheimer's disease is also characterized by abnormal proteins in the brain. Alzheimer's disease is also associated with a number of significant gastrointestinal dysfunctions, including constipation.

Again, I think it's too early to say that we've pinpointed exactly which of these diseases originate in the gut, but I think this type of study and others like it really shows that the gut and the brain are very closely connected. It's not a one-way street where the brain dictates what's going on in the gut, as we often think about the gut-brain connection.

When we're nervous or stressed, we often feel our stomach lurch or have the sudden urge to go to the bathroom before our turn to sing karaoke. This is one pathway of communication between the gut and the brain, but we're only just beginning to understand how much of an impact the gut has on the brain.