The Gastrointestinal Effects of Parkinson's Disease

Surveys show that between 20% and 40% of people with Parkinson's disease (PD) suffer from serious constipation (fewer than three bowel movements per week). Larger numbers of people with PD have related gastrointestinal issues such as bloating, a feeling of fullness and nausea. As the disease progresses, all of these GI problems become more common. In rare cases, serious complications—such as megacolon (enlargement of the colon) and perforation or tearing of the colon—may arise from these GI problems.

The connection between the two may seem odd on the surface, but research shines some light on these unpleasant consequences of the disease.

A large survey of healthy people who were followed over several years (as part of the Honolulu Heart Study Program) revealed that men who reported having less than one bowel movement daily had a 2 to 7 times higher risk of developing PD than that of men who had daily bowel movements; their risk was four times higher than that of men who had two or more bowel movements a day.

This body of data has led some to suggest that constipation is an early manifestation of the disease process itself and may predate motor symptoms of PD by years. The cause and effect relationship between constipation and PD is being actively researched. One theory suggesting a causative role of constipation in the development of Parkinson's is that if material moves slower through the colon, any toxic substance that is ingested has a longer time to be absorbed into the system. Once absorbed in large quantities, these toxic substances can damage dopamine-producing cells, putting an individual at greater risk for Parkinson's. However, in individuals already diagnosed with the disease, the hallmark lack of sufficient amounts of dopamine can directly affect gastrointestinal (GI) functions, slowing down the transit of material through the colon.

What Can Be Done About These Unpleasant GI Problems?

Unfortunately, research studies on GI problems related to PD have been few and far between, so healthcare providers do not have any tried and true methods to deal with them. Some of the drugs to treat GI problems in people without PD cannot be used for those with PD because these drugs (Metoclopramide hydrochloride) negatively impact dopamine systems in the brain.

If you have PD and experience constipation, it makes sense to try to use safe and simple methods to address this issue before you add new drugs to your daily regimen. Increasing dietary fiber and drinking lots of water and other fluids is a reasonable first step in treatment. If your healthcare provider approves it, you might also consider taking fiber supplements, such as psyllium or methylcellulose. If these simple methods don’t work, your healthcare provider might consider giving you a stool softener or a laxative.