IBS and anxiety are unfortunately very much connected, with up to 40% of IBS patients also suffering from an anxiety disorder. Why is this the case and what does it mean for treating IBS? It's all down to the gut-brain connection.

Higher levels of anxiety are associated with worsening IBS symptoms. In one study, people with higher levels of anxiety reported higher symptom severity for pain, cramping and bloating and lower quality of life. However, anxiety does not cause IBS or vice-versa, the disorders only exacerbate each other.

IBS and mental health issues such as anxiety and depression commonly occur together . Up to 40% of IBS patients also suffer from an anxiety disorder. Anxiety is common in people with IBS, and gastro-intestinal specific anxiety describes thoughts and emotions related to the digestive system. These feelings arise out of fear of sensations in the GI tract, and that events may trigger a flare-up of symptoms.( 4 )

Anxiety is a mental disorder of persistent fear and worrying, and anxiety disorders affect 20% of the population.( 2 ) According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), anxiety disorders may be classed as panic disorder, obsessive-compulsive disorder, and generalised anxiety disorder. Common symptoms of anxiety disorders include nausea, restlessness and shortness of breath.( 3 )

IBS and Mental Disorders

Anxiety disorder is one of several mental disorders linked to IBS. These include:

Depression

Post-traumatic stress disorder (PTSD)

Panic disorder(5)

What causes IBS?

To understand the link between anxiety and IBS, it is important to understand the cause of IBS. Several theories have been put forward to explain the origin of IBS. Traumatic life events, periods of stress and food allergies and illnesses have been suggested to play a role in the development of IBS. Scientific theories suggest several additional factors may lead to IBS developing and persisting:

Altered pain perception

Increased gut sensitivity

Stress: acute or chronic

Problems of the immune system(6)

IBS worsens anxiety

The method of action for IBS worsening anxiety disorder is straightforward. Symptoms of IBS such as cramping, bloating and abdominal pain are unpleasant and contribute to mental distress. These feelings of worry or concern over of IBS symptoms and unexpected flare-ups worsen the anxiety disorder. The financial and social stresses of IBS may also contribute to the development and persistence of anxiety.

IBS has been shown clinically to have a devastating toll on one’s psychological state. One study showed 38% of IBS patients had attended multiple specialist appointments for a third or fourth opinion had experienced suicidal thoughts. This finding explains how anxiety is worsened by IBS.(7)

Anxiety worsens IBS

How anxiety may cause or worsen IBS is less clear. It is thought that anxiety disorder and IBS are linked together by abnormal initiation of the ‘fight or flight’ response. In this view, people with anxiety disorder and IBS overreact to perceived sources of danger. These individuals may interpret both environmental cues and sensations in the gut as harmful, causing both anxiety and IBS.

Biologically, the division of the nervous system that links to the gut to the brain (‘gut-brain axis’) is likely to be involved in this process. A model taken from psychiatry known as the biopsychosocial model may also help explain the connection between anxiety and IBS.

The Gut-brain axis

The gut-brain axis is a two-way communication channel between the GI tract and the brain. It helps to explain how anxiety disorder may trigger IBS and vice-versa.

The gut and brain may influence each other in several ways. Microbes in the colon have been shown to affect mental health, and may even cause psychological illnesses such as anxiety disorder and depression. This occurs as a direct impact of the microbes themselves or their impact on permeability and inflammation in the GI tract. The impact of these microbes also implies that diet can have a direct effect on mental health.(8)

The brain also influences the gut, as the GI tract contains over 500 million neurons that connect to the brain via the nervous system. The stomach and intestines are lined with millions of nerve cells, which pass messages from the gut to the brain and vice versa. These signals are transmitted via the vagus nerve. The combination of these two pathways explains how anxiety may influence IBS may influence one another.(9)

Biopsychosocial model

In addition to the gut-brain axis, the biopsychosocial model helps to explain the link between anxiety and IBS. This model, conceived in 1977, refers to the connection between human biological, psychology, and social interaction. It explains how social experiences such as trauma may lead to psychological and in turn, biological effects in individuals. It also helps to explain how biological processes in IBS such as distension of the bowel may influence psychological distress and anxiety.(10)

Treatment for IBS and Anxiety

Both anxiety disorder and IBS are treatable conditions despite there being no cure. IBS has been effectively treated with several therapies including hypnotherapy, CBT, mindfulness-based treatment, anti-depressants and elimination diets such as low FODMAP.

Anxiety disorder is most often treated using psychological therapies such as CBT, hypnotherapy and coping strategies, or anti-depressant medication. Therapies targeting the nervous system, such as hypnotherapy, CBT and anti-depressants may treat symptoms of both IBS and anxiety.

Below is a list of treatments that may be beneficial in both IBS and anxiety disorder.

1. Anti-depressants

Antidepressants are not only prescribed for psychiatric conditions such as anxiety and depression; they are also useful in treating IBS. Two classes of antidepressants commonly prescribed are:

Tricyclic antidepressants : Tricyclic antidepressants are well-supported for IBS. A 2015 study assessing several clinical trials found Tricyclic antidepressants improved overall symptoms of IBS more than comparable antidepressants. Tricyclics in particular may be used to treat abdominal pain in IBS and work best for diarrhea-predominant IBS.(11)

: Tricyclic antidepressants are well-supported for IBS. A 2015 study assessing several clinical trials found Tricyclic antidepressants improved overall symptoms of IBS more than comparable antidepressants. Tricyclics in particular may be used to treat abdominal pain in IBS and work best for diarrhea-predominant IBS.(11) Selective serotonin reuptake inhibitors (SSRIs): These antidepressants are less strongly supported treatment for IBS but have been used successfully in some patients. SSRIs are commonly prescribed for anxiety disorders and are effective in constipation-predominant IBS.(12)

2. Hypnotherapy

Hypnotherapy involves progressive relaxation and hypnotic suggestion. This form of therapy has been adapted to treat functional gastrointestinal disorders and been shown effective for IBS in several studies. In one study, six weeks of hypnotherapy lessened IBS symptoms in 70% of patients, an effect equal in effect to that of the low FODMAP diet. Hypnotherapy also benefited patients in this study by reducing psychological scores for anxiety.(14)

Hypnosis is not generally considered a treatment for anxiety by itself, but an aid to psychotherapy. The hypnotic process involves relaxation and allows people to probe more deeply into painful thoughts that may be hidden from the conscious mind and teach coping skills through experiential learning. Hence, anxious thought patterns can be more easily accessed and treated by techniques such as CBT.

3. Cognitive-Behavioural Therapy

Cognitive-behavioral therapy (CBT) is a type of talk therapy that treats both anxiety disorders and IBS. CBT involves relaxation techniques, cognitive restructuring, exposure techniques, stress management, and teaching patients to challenge negative thoughts.

Cognitive restructuring is a CBT technique that allows patients to avoid obsessive thought patterns relating to IBS, to reduce symptoms. Patients are encouraged to build an awareness of the connection between distorted thinking patterns and digestive symptoms.(13)

Relaxation strategies such as diaphragmatic breathing activate the parasympathetic nervous system and promote normal digestion. This may help to lessen gastrointestinal symptoms.(13)

Exposure techniques involve the patient overcoming fearful situations by confronting them. In IBS, these fears may be tension or other sensations in the gut or eating feared foods.(13)

4. Diets for IBS

Diets that eliminate foods known to trigger symptoms are commonly prescribed treatment for IBS. Monash University has developed a diet, low FODMAP diet, which has been shown in numerous studies to reduce IBS symptoms in 70% of patients. The low FODMAP diet eliminates common molecular triggers of IBS (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols).(15)

Following an elimination diet to relieve IBS symptoms may benefit anxiety disorder by reducing anxious and obsessive thoughts relating to the GI tract.

A Word from Mindset Health

The connection between anxiety and IBS is complex. Both conditions are unpleasant and may interfere with daily activities. What remains clear is the importance of treating the two conditions together, rather than individually, and the value of adding psychological treatments to standard medical care. This will lead to the best health outcomes in patients.

Outdated views of IBS as a purely or purely psychological condition are being updated by research into the gut-brain connection. Future research may provide doctors more tools to identify and treat complex disorders that involve both the GI tract and nervous system.