Many of the posts in this blog tend to focus on trauma, stress and how what happens to us affects how the gut feels and misbehaves, but please don’t conclude that I necessarily think that IBS is ‘all in the mind’. It’s not and I don’t! But neither is it ‘all in the gut’.
Traditionally, medicine tends to treat the body as a collection of modules. We have specialists for the gut, the brain, the lungs, the heart, and many other body parts and systems – even the middle ear and the pelvic floor. We also have specialists for the mind, which some physicians think is part of the nervous system and others ‘the ghost in the machine’, misunderstood and poorly regarded. This mechanical model works well for those diseases that specifically attack one organ and system. Specialists can scan the offending part, treat it with drugs, blast it with radiation, remove it and even replace it. That is the miracle of modern medicine.
Infections, trauma, genetic defects and even cancer can all be treated, but as the those diseases are picked off, diagnosed and treated, it has left a whole raft of ill defined illnesses or syndromes for which there is no specific cause, clear diagnosis or effective treatment. The Irritable Bowel Syndrome (IBS) is one of those. Although by definition, it is a disease of the bowel, it also affects the back, the stomach, the bladder, the muscles and many other parts of the body, and it is strongly associated with anxiety, depression and other psychiatric ‘conditions’. Moreover IBS overlaps with other unexplained illnesses, such as functional dyspepsia, fibromyalgia, chronic fatigue syndrome, temporo-mandibular joint dysfunction, headache, backache and many others. It is by no means ‘all in the gut’.
Human beings are integrated organisms, not a collection of separate parts nor cut off at the neck. Everything is interconnected and works as a whole so that if one organ starts to malfunction, other parts are affected as well. If we have a chest infection, we not only have a cough and are short of breath, we also also tired, our muscles ache, our head hurts, we feel weak and faint and may not want to eat. The chest infection affects our whole body, causing us to stop, rest and allow healing to take place. Even pain is perceived in the brain and referred to the ‘affected’ body part, whether or not there is any tissue damage. Similarly, if we are shocked and traumatised by something dreadful, the same systems are activated and we feel ill in our bowels, our stomach, our head, our muscles; everywhere. And of course, we also feel tired, anxious and depressed. The point I am making is that every illness, irrespective of whether it is generated by tissue damage or induced by traumatic life situations or events, can dysregulate the autonomic nervous system, the endocrine system and the immune system causing a similar array of unexplained symptoms.
One common sign of illness is an increase in sensitivity. People with urinary frequency have an increase in bladder sensitivity, people with indigestion have an increase in gastric or duodenal sensitivity, people with fibromyalgia have sensitive knots in their muscles, people with headaches sensitivity in the large muscles supporting the neck and people with IBS have increased rectal or intestinal sensitivity. Irrespective of whether visceral sensitisation is produced by an attack of gastroenteritis, food allergy, bile acid malabsorption, depletion of the micro-biome, or is caused by a traumatic life event, the symptoms are similar and are triggered by anything that stimulates the gut such as a rise in emotional tension or a diet that contains poorly absorbed fermentable foods.
A vastly important spin-off from the Human Genome Project has been the characterisation of the colonic micro-biome. Scientists had known that the colon contained teeming numbers of bacteria for over a hundred years. In the early years of the last century, it was assumed these were pathogenic and were best eliminated. So, fashionable surgeons such as London’s Sir Arbuthnot Lane used to conduct colectomies for everything from knock knees to dementia and short sightedness. It is only in the last few years that we have come appreciate that, contained within our colon, is a metabolic powerhouse with a capability that exceeds that of the liver, is infinitely responsive to changes in diet and life style, in particular the chemicals we ingest, and able to influence the function of every part of our body. This colonic biomass has enormous benefit for the salvage of energy, nutrients, salt and water from poorly digested food, the production of vitamins and the development of the gut immune system. But like every ecological system, when its diversity is depleted, the colon becomes damaged and there are knock on effects throughout the rest of the body including the brain and mind.
In his recent book, ‘Between the Mind and Gut’, Dr Emeran Mayer has described how changes in the microbiome can affect the amount of weight we put on, cause pain in our joints and even influence the way we think. Depression, Dementia and Parkinson’s Disease have all been linked to colonic microbial maladaptation. This has led to speculation that we will soon have a specific microbial signature for IBS. I think this is unlikely. Although the microbiome in IBS is less stable and diverse than it is in people who do not have gut symptoms, this is probably a non-specific effect of changes in diet, physiology and drug treatment in IBS. As such the alterations in the microbiome is another factor underlying dysregulation. I suspect it will take many years before we fully understand how changes in the microbiome interact with the endocrine, immune and autonomic nervous systems to generate the variable symptoms of IBS and longer still before we learn to regulate it. Confronted with this degree of complexity, no wonder there is no clear conclusion regarding the efficacy of probiotics.
So to conclude, gone are the days when common diseases, like IBS, had a single cause. Most of those have been solved. We are now left with a number of interacting, complex, long-term disorders of regulation, in which multiple factors interact to result in individual variations on a theme of common symptoms presentations, often expressed in the gut. These are more likely to respond to an the idiosyncratic combination of therapies, life style changes and symptomatic treatments. As ever, you, the patient, are best placed to manage their own IBS given appropriate options and guidance.