Why does Parkinson's cause constipation?

When people think of Parkinson's disease they often think of tremors however often people who actually have Parkinson's are more concerned by the symptoms that are not to do with movement and tremors (non-motor symptoms). The commonest of these symptoms are constipation, tiredness, difficulty sleeping, anxiety and needing to pass urine multiple times at night. These symptoms are not always as immediately obvious to people without Parkinson's but they can be extremely troubling. In this blog I want to talk a bit more about constipation and why people with Parkinson's get constipation.

Constipation is when it is more difficult to go for a poo or when the amount of time between opening your bowels increases. Usually your poo will become a lot harder when this happens and sometimes can result in a bloated feeling and pain in your tummy. So the question is how does Parkinson's, a brain disease, affect your bowels in this way?

The answer lies in looking at the large intestine. This is a large pipe near the end of the path from your mouth to your bum (the GI tract). By the time your dinner reaches the large colon it has mainly been digested and had all of the useful vitamins, protein and carbohydrates removed from it. This means that when your dinner reaches the large colon it is made up of waste products (poo) and lots of water; in fact it is so watery at this point that it is completely liquid. The role of the large colon is to turn this liquid into a solid poo and to get the water out of it so that you can stay hydrated. So what changes in Parkinson's disease?

In Parkinson's disease if you measure the amount of time it takes a piece of food to move from the beginning of the large intestine to exiting out of your bum it would take double the amount of time that it would take a healthy person. In other words: poo moves through the large intestine at half the speed if you have Parkinson's. Because the large intestine is so good at draining water from your poo, the poo becomes much drier and harder as the large intestine has double the amount of time to remove as much water as possible. This explains why people with Parkinson's have drier harder poos and subsequently have more constipation.

The large intestine pushes food along it by tensing the muscles around it in a rhythmic way that propels the poo downstream. Like the rest of the body, in Parkinson's, these movements become much slower. The reason for this is not as clear but is probably due to the layer of nerve cells around the gut wall called the enteric nervous system. Studies where they have looked at samples of the gut wall have found build ups of Lewy Bodies (the characteristic thing found in the brain in Parkinson's) also in the gut wall. It is possible that this build up is what also causes the slowness in the gut.

It is important to remember that there are many other things that cause constipation other than Parkinson's. There are many medications that can be tried to help improve constipation but some of the simple things that can help are increasing the amount of water you drink or increasing the amount of fibre that you eat, but discuss with your doctor if this is a problem for you.

Curr Treat Options Neurol. 2018 Oct 25;20(12):54. doi: 10.1007/s11940-018-0539-9.

Gastrointestinal Dysfunction in Parkinson's Disease.

Pfeiffer RF

Author information

Abstract

PURPOSE OF REVIEW:

During the past 25 years, there has been an explosion of information regarding the occurrence of gastrointestinal dysfunction in Parkinson's disease. In this review, the clinical features of gastrointestinal dysfunction in Parkinson's disease will be described and information regarding the potential role of the enteric nervous system and the gut microbiome in the genesis of Parkinson's disease will be addressed.

RECENT FINDINGS:

Recognition is growing regarding the role that gastroparesis and small intestinal dysfunction may play in Parkinson's disease, especially with regard to erratic responses to anti-Parkinson medication. The presence of enteric nervous system involvement in Parkinson's disease is now well established, but whether the enteric nervous system is the starting point for Parkinson's disease pathology remains a source of debate. The potential role of the gut microbiome also is beginning to emerge. Gastrointestinal dysfunction is a prominent nonmotor feature of Parkinson's disease and dysfunction can be found along the entire length of the gastrointestinal tract. The enteric nervous system is clearly involved in Parkinson's disease. Whether it is the initial source of pathology is still a source of controversy. There also is growing recognition of the role that the gut microbiome may play in Parkinson's disease, but much more research is needed to fully assess this aspect of the disorder.

Non-motor features of PD... new report from the HPFS

Here we see evidence to support the fact that it you have a combination of smell loss, probable REM sleep behaviour disorder and constipation, you are more likely to have Parkinson's... this is not surprising because we have seen this in lots of other studies but it is nice to see it all brought together in one study.

The comments are as follows... odds ratios (ORs) in this context are a little bit meaningless. How does one interpret an odds ratio of 160, let alone an OR of 1323 other than to say it looks like a lot?? By comparison, if you look at ORs between an established risk factor (such as smoking) and disease outcome (such as lung cancer), the ORs are between 20-40. It is not a criticism of the approach; in PREDICT-PD we too have traditionally modelled ORs. However, we rank an individual's OR against the ORs of everyone else in the cohort, meaning that, whilst not their literal risk, it is correct in relation to all other participants in the cohort.   

The combination of the three factors has a positive predictive value of 35% - meaning that if you have all three together there is a 35% chance of you having a diagnosis of PD. Long story short... these three non-motor features, in combination, still look like some of the most useful for recognising PD... either in those that have a diagnosis or who are in the prodromal phase...

- Alastair Noyce

https://jnnp.bmj.com/content/early/2018/08/03/jnnp-2018-318275.long

Autonomic dysfunction in Parkinson's disease: A prospective cohort study

The non motor symptoms of PD are so important. This study shows how autonomic dysfunction worsens significantly over short periods of follow up in patients that have a diagnosis of PD. We already know from other studies that autonomic dysfunction is a marker of Parkinson's disease severity and heralds a shorter survival of patients with PD. 

There has been quite a lot of focus on sleep, cognition and mood as non motor features of PD but we are not adequately addressing symptoms and consequences of autonomic dysfunction and studies such as this highlight the importance. Previously, marked autonomic involvement used to raise the suspicion of an alternative parkinsonian disease (such as multiple systems atrophy) and although autonomic dysfunction is a prominent feature of MSA, it is also very prevalent in PD. 

Of course autonomic dysfunction also often precedes a diagnosis of PD, whether in the form of orthostatic hypotension, or more commonly with constipation, erectile dysfunction or urinary symptoms. We at PREDICT-PD have a longstanding interest in how symptoms of autonomic dysfunction can be used to identify those that might one day go on to be diagnosed with PD...

Alastair Noyce

Mov Disord. 2017 Dec 26. doi: 10.1002/mds.27268. [Epub ahead of print]
Merola A1, Romagnolo A2, Rosso M1, Suri R1, Berndt Z1, Maule S3, Lopiano L2, Espay AJ1.

http://onlinelibrary.wiley.com/doi/10.1002/mds.27268/full

BACKGROUND: Dysautonomia is a frequent and disabling complication of PD, with an estimated prevalence of 30-40% and a significant impact on the quality of life.

OBJECTIVES: To evaluate the rate of progression of dysautonomia and, in particular, orthostatic hypotension, in a cohort of unselected PD patients, and assess the extent to which the progression of dysautonomia affects activities of daily living, health-related quality of life, and health care utilization in PD.

METHODS: We recruited 131 consecutive patients into a 12-month, prospective, observational cohort study. Clinical measures included the International Parkinson and Movement Disorder Society/UPDRS, the Scale for Outcomes in Parkinson Disease-Autonomic, the Orthostatic Hypotension Symptoms Assessment, and orthostatic blood pressure measurements. Health care utilization was quantified as the number of hospitalizations, emergency room visits, and outpatient clinic evaluations.

RESULTS: The overall severity of autonomic symptoms, as measured by the the Orthostatic Hypotension Symptoms Assessment total score, worsened by 20% over 12 months (P < 0.001), with an overall increase in orthostatic hypotension prevalence from 31.1% to 46.7% (P < 0.001). Worsening of autonomic symptoms was independently associated with deterioration in daily living activities (P = 0.021) and health-related quality of life (P = 0.025) adjusting for disease duration, cognitive impairment, and motor severity. Regardless of symptomatic status, orthostatic hypotension was associated with greater deterioration in daily living activities, health care utilization, and falls (P ≤ 0.009) compared to patients without orthostatic hypotension.

CONCLUSIONS: The severity of autonomic symptoms progressed by 20% over 1 year and was independently associated with impairments in daily living activities and health-related quality of life. Symptomatic and asymptomatic orthostatic hypotension were both associated with increased prevalence of falls and health care utilisation.

© 2017 International Parkinson and Movement Disorder Society.