Unexplained and persistent constipation in adults is associated with an increased risk of PD. Nearly one third of patients will have been diagnosed with a GI disturbance within the year prior to PD diagnosis (1), and many more will have noticed a change in bowel habits without having received a formal diagnosis. There is a preponderance of data to support this.
In 2001, the Honolulu Heart Program (2), a large population-based prospective study, showed a 2.7-fold risk of developing PD for men with less than one bowel movement daily, when compared with men having one or more daily. In 2011, a large prospective study of over 100,000 people also showed that over the next six years, relative risk of developing PD was was nearly five times greater for men who had one bowel movement every three days or less (3), compared with men having a daily BM. A 16-year prospective study of 8,166 people with PD and 46,755 without PD in the United Kingdom reported that, in the two years prior to diagnosis of PD, 32% had constipation (4).
Unfortunately, the prevalence of GI disturbances in PD increases with age and longer duration of disease. Ultimately, constipation is reported by almost 60% of PD patients (5).
The reasons for constipation in PD are complex. As discussed in the Spring 2016 issue of this newsletter, in the article “What’s so bad about alpha-synuclein?,” disease-specific pathology may be seen in the gut years prior to the development of motor symptoms of PD, and that pathology may be part of the culprit leading to disease (see also the slides from the April talk on alpha-synuclein).
The problem seems to arise from a slowing down of the gut in PD. There may be a delayed gastric emptying, followed by slow transit of stool. This allows the over-production of bacteria which results in gas, and sometimes, colic. Another problem is that stool is supposed to dry out as it moves through the colon. The slower it goes, the drier it gets, and in a self-perpetuating cycle, the drier it gets, the slower it goes. Some patients with PD have such slow transit they develop a hard stool called a fecalith, or “feces rock.” In rare cases, all movement of stool may stop, a medical urgency/emergency known as impaction.
So, what can a person with PD do about constipation?
First, educate yourself. Drugs used to treat many conditions, including those meant to help PD, can cause constipation. Some of these drugs include anticholinergics such as trihexyphenidyl (Artane), benztropine (Cogentin), and even carbidopa/levodopa (Sinemet). Other medication-induced causes of constipation include narcotics, antihistamines, tricyclic antidepressants such as amitriptyline, certain antipsychotics, some antihypertensives, lipid-lowering drugs, calcium supplements, iron tablets, and even antacids (APDA). Before stopping any of these medications, check with your prescribing doctor.
Daily exercise is helpful, and you should check with your doctor about any recommendations or limitations you may have.
There are certain foods and beverages that may lead to, or enhance, constipation, for example, cheeses, red meats, dairy products, processed foods, fast food, fried food, and “junk” food, are all culprits (your mother was right). Caffeine, while stimulating bowel movements in some, is actually a diuretic, which may dry the stool out even more. The same is true of alcohol. If you drink either caffeine or alcohol, compensate with water. People with constipation should stay hydrated, and eat foods which aid in digestion, such as raw vegetables and fruits, dried prunes, bran, and high-fiber foods. To learn more about diet and find a recipe for a high fiber mix that may help, see the APDA handout on constipation (6).
Generally, one should eat at regular times, and try to have a bowel movement about 30 minutes following the morning meal. This naturally occurs due to a phenomenon called the gastrocolic reflex, in which the brain sends messages to the GI tract to defecate when the stomach is distended.
The Guidelines
In 2006, the American Academy of Neurology (AAN) wrote in their guidelines for the treatment of non-motor symptoms of PD that increased water and dietary fiber intake have shown clinical benefit in relieving constipation (7). The AAN found only limited, or “weak” evidence regarding medications at the time, but supported isosmotic macrogol (polyethylene glycol), available as Miralax over the counter, which “may be considered to treat constipation in PD.” The benefit of Miralax is that it is not systemically absorbed, and instead, pulls water like a sponge into the gut, where it can help hydrate stools. Soluble fiber has the same effect and is not absorbed into the bloodstream. However, using Miralax or fiber alone is often inadequate.
Calin Stoicov, M.D., a gastroenterologist at Mid Coast Medical Group in Brunswick, points out that we should be careful in how we define constipation. The definition is not solely based on the frequency of bowel movements, though less than three weekly is a place to start the description. Also, there is straining at lumpy, hard stools, a sensation of incomplete evacuation, and a sensation of rectal obstruction or blockage with 25% of bowel movements.
Stoicov noted that, broadly, the constipation in PD is treated similarly to other forms. “The agents are divided into four groups: bulking agents such as dietary fiber or artificial fiber (Benefiber, Citrucel), osmotic agents (Miralax), stimulants (senna), and pharmacological agents (Amitiza or Linzess).” He noted that constipation is usually not painful. If there is pain associated with constipation, one should think of another culprit, such as irritable bowel syndrome (IBS). That patient should be evaluated by a physician. For patients with PD who have simple constipation, he recommends starting with Miralax, and to use it liberally, as it is not absorbed. Some patients will try lactulose, but should be careful, as it may be more likely to cause bloating. When patients are prescribed Amitiza or Linzess, they may find more success, but should be careful as these medications may be a little too successful, and result in diarrhea.
People should not expect immediate results, either. I often hear that this or that approach did not help after a few days, so it was abandoned. Or, some people will note that they may have a loose stool on some days, and a hard stool once a week. In this case, there is too much dried out stool in the colon, and loose stool is moving around it. It is better in that case to have a regular, daily bowel regimen, to keep everything moving. Per Dr. Stoicov, medications are usually effective within about a week. He notes that stimulants, such as the herbal laxative senna, have a tendency to stain the colon black, which may be seen during colonoscopy. Some data suggest that this condition, known as melanosis coli, might predispose to polyps.
Finally, it is not good to wait until constipation becomes a problem. Be proactive, educate yourself, and promote good bowel health. This really is a situation wherein you get out what you put in.
1. Makaroff et al. Gastrointestinal Disorders in Parkinson’s Disease: Prevalence and Health Outcomes in a US Claims Database. J Parkinsons Dis. 2011;1(1):65–74.
2. Abbott et al. Frequency of bowel movements and the future risk of Parkinson’s disease. Neurology. 2001;57:456–62.
3. Gao et al. A prospective study of bowel movement frequency and risk of Parkinson’s disease. Am J Epidemiol. 2011;174:546–51.
4. Schrag et al. Prediagnostic presentations of Parkinson’s disease in primary care: a case-control study. The Lancet Neurology, 2014;14(1):57-64.
5. Magerkurth et al. Symptoms of autonomic failure in Parkinson’s disease: prevalence and impact on daily life. Clin Auton Res. 2005;15(2):76–82.
6. http://www.apdaparkinson.org/uploads/files/Constipation-8-25-15-er0.pdf
7. https://www.aan.com/Guidelines/Home/GetGuidelineContent/409
