Bowel and bladder problems cause much distress for individuals with Huntington's disease (HD) and their families. How common are these complaints? How "real" are these complaints? Are these just obsessive behaviors? Are they imagined and just "in the head"? Or what?
Not just in the head: There aren't many answers to questions about bowel and urinary problems in HD. Though we know it happens, this author found only one mouse model study of bowel function and only one published study of urinary bladder problems in individuals with HD. We can learn from this latter study in HD, and from others published in Parkinson's disease (PD) that these problems are frequent and caused directly by the disease: So not just in the head.
Adding insult to injury for bowel and bladder problems in HD, physical inactivity and several of the medications used in treatment of other symptoms cause side effects that further add to both bladder and bowel problems.
Why do bowel/bladder symptoms occur in HD? The short answer is that nerve damage caused by HD is not only in brain. Bowel and urinary-related nerves belong to the "autonomic" system. Think of this system of nerves and the muscles they supply as being able to work automatically. This system coordinates movement of food through different parts of the bowel. Similarly nerves that supply muscles to the bladder "sense" when the bladder is full. The ability to have a bowel movement or to urinate is more complex, requiring communication and coordination between autonomic (automatic) and voluntary (the ones we can control) motor systems. Damage to different nerves cause changes in symptoms over the course of disease. For instance, too much activity (as in a hyperactive bladder) in earlier disease, then incontinence or leaking of urine in later disease.
How frequent and important are urinary bladder/bowel problems in HD? The short answer to this question is "not known". However several survey studies in PD may give us information that is similar to HD. These studies show that these symptoms are:
- Frequent: affecting 60-80% of individuals
- Important: correlating with poor quality of life and degree of "suffering"
- Often not reported to their doctors
The PD research community has paid attention to these symptoms by adding questions about bladder and bowel function to their PD Non-motor Symptom Scale (NMS). The HD research community has no equivalent scale.
Urinary bladder dysfunction in HD: There is recent study by Podnar and colleagues [Kolenc M 2014] of 54 clinic patients with that gives information on bladder problems in HD:
- Bladder overactivity was more common in early disease
- Incomplete bladder emptying more common in middle stages
- Urinary leaking or incontinence more common in late stage
- Degree of dysfunction increased with stage of disease
- Severity of dysfunction correlated with poor quality of life and depression
Bottom line is that bowel and bladder symptoms in HD are valid and are, at least in part due to the disease. Of course there are other causes for both. For instance urinary leaking in women is more common following childbirth and menopause. Similarly men with large prostrates have trouble starting urination and cannot completely empty the bladder.
Other causes include lack of physical inactivity, caffeine beverage over use, and dehydration or excessive water drinking. Very big factors are side effects of drugs used in treatment of other symptoms of HD. Various antipsychotic medications and antidepressants can cause either constipation or diarrhea. Some increase difficulty urinating. Narcotic drugs are the main culprits of constipation. Drugs that treat overactive bladders cause constipation and can worsen cognition. Finally, worry about bowel and bladder accidents can lead to obsessive behaviors. And the list goes on . .
Treatments: While there is little known about these problems in HD, there is even less known about effective treatment specific to HD. Regular toileting is more helpful for hyperactive bladder than medications that may cause constipation and impair cognition. The treatments for constipation are not different than those for the general population. If trips to the bathroom take on an obsessive complusive (perseverative) character, appropriate treatment of this symptom may be helpful.
Author comments: Bladder and bowel problems in HD are real. The first part of treatment for each is "validation", or giving recognition that the symptoms are real and not just "in their head". The next part of treatment is empathy. These are not just attention-getting complaints, nor are they primarily psychiatric in origin. They are real problems that have real negative implact on quality of life.
Kolenc M, Moharić M, Kobal J, Podnar S. Bladder dysfunction in presymptomatic gene carriers and patients with Huntington's disease. J Neurol. 2014 Dec;261(12):2360-9. doi: 10.1007/s00415-014-7494-5. Epub 2014 Sep 20. PubMed abstract