Constipation in Parkinson’s Disease

by Neil R. Greenspan, MD, FACG

What is constipation and why is it important?

Constipation is the most common gastrointestinal complaint affecting approximately 15 % of the North American population. Certain subgroups have an even higher risk (e.g. in the over 65 population 26% of men and 34% of women are affected). It is remarkable that for such a common disorder there is great debate on the definition of constipation. A committee of experts in the field include in the definition 2 or more of the following: abnormalities of stool frequency (less than 3 times weekly), abnormal stool form, straining at stool, sense of incomplete evacuation or obstruction to passage of stool, and the use of manual maneuvers to aid in passage of stool (>= 25% of the time).

What causes constipation?

Constipation is almost always due to slow passage of stool through the colon (large bowel) or anus/rectum as passage through the small bowel is typically normal. Constipation may be associated with a number of medical conditions including diabetes and underactive thyroid. Of great importance to the readers of this newsletter is that many neurologic disorders (including Parkinson’s disease, multiple sclerosis, and spinal cord injury) are associated with constipation. In addition to the neurologic disease itself, reduced mobility may aggravate constipation. Many drugs used to treat neurologic disorders and other diseases may worsen symptoms of constipation. It is important for patients to notify their physicians if they think their medications have affected their bowel movements as in most cases this side effect can be easily managed.

How is constipation evaluated?

The evaluation of constipation typically starts with a thorough history and physical exam to look for medications or other conditions that may contribute to constipation. Testing may initially include checking the stool for blood or testing the blood for anemia that may indicate gastrointestinal bleeding. Blood tests to evaluate for diabetes or thyroid disorders may be indicated if not performed recently. Typically a colonoscopy would be recommended for any patient who is due for colon cancer screening according to current guidelines. Other tests may require referral to a gastroenterologist.

How is constipation treated?

The treatment of constipation typically begins with optimization of fiber and fluid intake. While fiber may be increased through changes in diet, it can be challenging to get people to change their long-standing dietary habits. For many people, the addition of bulking agents such as psyllium or methylcellulose is an inexpensive and simple way to increase fiber. Polyethylene glycol, guar gum and lactulose are other choices that have less texture though may be more expensive than bulking agents. For an occasional patient stimulant laxatives or prescription medication is necessary to control symptoms of constipation.

Neil R. Greenspan, MD, FACG Gastroenterology Associates Providence, RI