Gastrointestinal Diseases and Parkinson's

While Parkinson’s disease (PD) is thought of as a condition that affects the brain, research has shown that PD may actually begin in the enteric nervous system, the part of the autonomic nervous system that controls the gastrointestinal organs.^1,2

The clumps of the protein alpha-synuclein (a hallmark of PD) that are called Lewy bodies can be found in the gastrointestinal tract before progressing to the brain.^1,2

Early signs

Many people with PD experience gastrointestinal symptoms, like constipation and a slower emptying of the stomach into the intestines, called gastroparesis.^1,2

Constipation may be one of the earliest symptoms of PD, prior to a person being diagnosed with the condition. There also seems to be a link between PD and gastrointestinal disease.^1,2

Inflammatory bowel disease

Inflammatory bowel disease involves chronic inflammation of all or part of the digestive tract. IBD primarily includes ulcerative colitis and Crohn’s disease. While both ulcerative colitis and Crohn’s can cause severe diarrhea, pain, fatigue, and weight loss, ulcerative colitis affects the colon.

Crohn’s disease most often affects the end of the small bowel (the ileum) and the beginning of the colon, although it can affect any part of the GI tract. Ulcerative colitis affects only the innermost lining of the colon, and it affects the entire colon. In contrast, Crohn’s disease can affect the entire thickness of the bowel wall, and it may leave patches of normal tissue in between areas of diseased intestine.^3,4

What is the cause?

The causes of IBD remain unknown. One possible cause is a malfunction in the immune system, and IBD is sometimes referred to as an autoimmune disease. Genetics also seem to play a role in the development of IBD, as IBD is common in people who have a family history of the disease.

Between 5-20 percent of people with Crohn’s have a first-degree relative (parent, child, or sibling) with IBD. However, most people with IBD do not have a family history. Research suggests that a combination of hereditary, genetic, and/or external factors contribute to the development of IBD.^3,4

Link between the two

Research has investigated the association between PD and IBD. Studies have found that there seems to be an increased risk of developing PD among people with IBD.

The risk is greater among those with Crohn’s disease. A higher rate of PD is also associated with IBD patients who have hypertension (high blood pressure), coronary artery disease, or depression.⁵

Several research studies are investigating the genetic link between PD and IBD. Mutations in LRRK2, which are the most common cause of familial PD, also seem to be associated with IBD. Other areas of research are looking into the link between PD and inflammation in the gut.⁶