What do we know about IBS? The answer is surprisingly little. There is no definitive cause, no specific pathology and no single effective treatment. It is and always was a concept, invented by medical opinion leaders to characterise bowel symptoms that could not be explained by cancer, colitis or any other specific disease. But over the last fifty years, it has assumed the status of a disease. Diagnostic criteria have been developed and changed again and again, management guidelines have been produced, many books have been written, but we all know that the amount written about any subject is always inversely proportional to the degree to which it is understood.
An illness that has no clear explanation must force us to question the paradigm from which we view it. Most medical professionals believe that the symptoms of bowel irritability are the common end result of a variety of specific pathological causes and mechanisms that will become more clear with time and research. But since IBS was first coined, no new causes of IBS have been established with absolute certainty.
It has always been part of the definition of IBS that coeliac disease and inflammatory bowel disease must first be ruled out and that may also come to include non-coeliac gluten sensitivity. Small Intestinal Bacterial Overgrowth has been proposed as a major cause of IBS on the basis of an early rise in breath hydrogen after a dose of lactulose, but the same result could be generated by rapid small bowel transit. People with IBS are said to have a depleted and unstable colonic microbiome, but that applies to many other illnesses and in so called healthy populations throughout the civilised world – and, as I wrote in a recent post, the use of probiotics is still unproven. Other putative diagnoses such as lactose intolerance, fructose intolerance, FODMAPs intolerance and bile acid malabsorption could be explained by increases in bowel sensitivity or rapid intestinal transit, physiological features that have long been associated with diarrhoea predominant IBS. Despite enormous amounts of research, the current paradigm of IBS has yielded few definite answers.
One of the most striking aspects of IBS is the extensive overlap between symptoms of IBS and other unexplained illnesses, such as functional dyspepsia, fibromyalgia, chronic fatigue syndrome, backache, headache, breathlessness, irritable bladder, and many more. It is uncommon to find patients with IBS, who do not also have symptoms referable to other bodily organs and systems. Psychological symptoms such anxiety, depression, frustration, shame and guilt are so prevalent in IBS, they deserve to be seen as part of the illness. This strongly suggests that much of what we call IBS is a much larger state of dysregulation or dysphoria affecting the mind and the various parts of the body. The reasons why some regions of the body are selected and not others may be associated, not so much with pathology as with meaning.
The concept of mind-body dysregulation would also be supported by observations that, for most people, IBS is not a stable illness; it can come and go according to what is going on in their lives and the concomitant changes in their life style. Moreover IBS and other unexplained illnesses are often instigated by loss or trauma.
If our social environment can disrupt the regulation of the body, then it seems most likely that this is mediated by the sympathetic and dorsovagal components of the autonomic nervous system. As such, it could be usefully tackled by holistic methods that restore security and control via the ventral vagal complex.
A paradigm shift for IBS from ‘a variety of undiscovered diseases’ to ‘the visceral expression of dysregulation’ could liberate patients from the hopelessness of an unexplained diagnosis with its miserable round of negative tests and failed treatments. Once the usual culprits, such as colitis and coeliac disease, have been screened out, patients might helpfully be assigned to the kind of holistic methods that apply ‘the vagal brake’ and optimise security, health and restoration, as I will attempt to outline in my next post. Such a change in perspective would offer a much needed stimulus to research that is not confined by distinct entities, but explores connections between different diseases, between the mind and the body and between different modalities of treatment.
Finally, the theory and practice of medicine is never straightforward and I am only too aware that I might be describing a false dichotomy. A more convincing diagnosis for SIBO and a more acceptable treatment or a specific change in one component of the microbiome. Doctors will still need to keep an open mind on game changing discoveries and seek to screen them out. On the other hand, there may be a time when dysregulation is seen as part of all chronic illness and holistic methods are more generally accepted to help patients regulate the fluctuations in their condition.