Explainer: what is Irritable Bowel Syndrome?
By Alex Ford, University of Leeds
Irritable bowel syndrome (IBS) is a chronic functional disorder of the gastrointestinal tract which affects up to 20% of people worldwide. In the UK and the US, about 10-15% of people have IBS – and most people will experience symptoms compatible with IBS at some point in their life. IBS affects both men and women but about two-thirds of sufferers are female. It is more common among young people.
The symptoms of IBS include recurrent abdominal pain or discomfort and changes in bowel habit, including diarrhoea and/or constipation, bloating and cramps. For many sufferers, the pain, discomfort and inconvenience of IBS can also affect them psychologically and emotionally.
Symptoms of IBS can come and go in bouts, often peaking during times of stress or after eating certain foods. For some, episodes can be weekly or daily and severity can range from mild acute discomfort to a debilitating chronic illness.
What causes IBS?
The exact cause of IBS remains unclear. It may be down to a number of factors including a change in your body’s ability to move food through your digestive system, increased sensitivity of nerves to pain signals from your gut, very mild inflammation, overgrowth of bacteria in the small bowel, or changes in the types of bacteria that are most commonly found in the large bowel.
Stress is often linked to IBS but it is not believed to be the cause, but rather a trigger or something that exacerbates symptoms. Stress can create a vicious circle where symptoms cause stress and stress worsens symptoms. Some studies have shown that patients with chronic emotional stress are more likely to develop symptoms compatible with IBS in the future.
There is no definitive test for IBS but doctors can positively diagnose it based on typical symptoms. Diagnosis sometimes needs to exclude other potential problems that may exhibit similar types of symptoms, such as Crohn’s disease.
How do you treat it?
Treatment for IBS is typically targeted towards the predominant symptom. So increased intake of soluble fibre may help constipation – and antispasmodic agents can help manage pain and cramping symptoms. These are frequently used as first-line therapies. Other treatment options with some evidence for their efficacy in IBS include certain antidepressants, such as amitriptyline; psychological therapies such as cognitive behavioural therapy and hypnotherapy, and some probiotics.
There are currently a number of effective short-term treatments available for patients with IBS, but, unfortunately, no drug treatment has so far been shown to alter the long-term clinical course of IBS. In other words there’s no cure.
Many sufferers often have to try several drugs before they find a treatment that works for them – and this can be expensive for sufferers and society as a whole. In one survey, only 8% of sufferers were very or extremely satisfied with available IBS treatments, and a third were not at all satisfied.
Many IBS suffers battle the symptoms over the long-term. In one study two-thirds of people still had symptoms that were compatible with IBS ten years later. In addition, many people suffer in silence and do not share the full extent of their condition with friends or family. This often makes IBS a very isolating and embarrassing problem.
Nevertheless, there has been some progress made in drug development for IBS. Thanks to the intense research efforts of scientists around the world several promising new types of drug therapy have emerged in recent years. Pro-secretory agents have been found to be effective in patients with IBS whose main problem is constipation. These include Linaclotide and Lubiprostone, which both stimulate cells in the large bowel to pump out fluid, which increases intestinal secretion and transit. Bile acid modulators are currently under investigation in IBS patients, with initial studies suggesting efficacy in diarrhoea-predominant IBS.
IBS is still very much a mystery in many ways. However, the number of novel agents in clinical development for the treatment of IBS is a reflection of our growing understanding of the pathogenesis of the condition. It also demonstrates the extent of the unmet medical need. Yet, with research efforts continuing into discovering new IBS treatments, there may be reasons for cautious optimism.
A better understanding of the impact of IBS on a person’s quality of life and mental health has also led to the development of specialist clinics that deal with emotional well-being as well as the physical symptoms of IBS. This will hopefully enable sufferers to get their life back on track.
Alex Ford has received funding from GE Healthcare and the Leeds Teaching Hospitals Charitable Foundation