Everything you need to know about disorders of the gut-brain axis (functional GI disorders)

Disorders of the gut-brain axis, also known as functional GI disorders, are a group of conditions that affect the digestive system without an identifiable structural or biochemical cause. These disorders are common in children.

This article provides an expert insight into these disorders, exploring what they are, how they are diagnosed, and what treatment options are available for them.

What are disorders of the gut-brain axis (functional GI disorders)?

Disorders of the gut-brain axis occur when there is a disturbance in the communication between the brain and the gut.

The gut-brain axis is a complex two-way network of communication between the central nervous system (the brain and spinal cord) and the enteric nervous system (the gut). This complex network plays a critical role in regulating digestion, gut motility, and sensation in the gastrointestinal tract.

In children with disorders of the gut-brain axis, this communication is altered, resulting in symptoms without any detectable structural or biochemical abnormalities in the digestive system. Common examples of these disorders in children include irritable bowel syndrome (IBS), functional dyspepsia, and functional abdominal pain.

Symptoms vary depending on the specific disorder but may include recurrent abdominal pain, bloating, nausea, constipation, or diarrhoea. In some cases, children may also experience fatigue, headaches, or difficulty eating due to early fullness.

What causes functional GI disorders in children?

The exact cause of functional GI disorders isn’t fully understood, but several factors are believed to contribute. One of the most significant influences is the gut-brain axis, which can lead to heightened sensitivity in the gastrointestinal tract or disruptions in normal gut motility.

Psychological factors, such as stress, anxiety or depression, can exacerbate these symptoms, because emotional distress can affect the gut-brain axis, increasing gut sensitivity or altering the release of hormones and neurotransmitters involved in digestion.

Additionally, disruptions in the gut microbiome - known as dysbiosis - can play a role in the onset and severity of these disorders. The microbiome, which consist of trillions of microorganisms in the digestive system, has profound impact on gut health and communication with the brain.

Genetic predisposition and a family history of functional GI disorders can also increase a child's likelihood of experiencing these conditions. Other factors, such as food intolerances, can trigger or worsen symptoms.

How are functional GI disorders diagnosed?

Functional GI disorders are diagnosed based on a careful evaluation of the child’s symptoms and medical history, along with a process of exclusion to rule out other conditions. The Rome IV criteria, a set of guidelines that provide specific diagnostic criteria, is often used to focus on symptom patterns.

A paediatric gastroenterologist will typically begin with a detailed discussion of the child’s symptoms, including their frequency, severity, and duration. A physical examination will then be conducted.

Depending on the symptoms, additional tests may also be performed to rule out other potential causes. These may include blood tests, stool analysis, or imaging studies such as ultrasound.

What treatments are available for managing these disorders?

Functional GI disorders don’t have a one-size-fits-all treatment in the traditional sense, but they are highly manageable with the right combination of approaches.

Dietary changes, which often involve identifying and avoiding trigger foods (such as lactose, high-fat foods, spicy meals, or certain carbohydrates), are a common first step. For children with IBS, a short-term low FODMAP diet - which reduces fermentable sugars - can also be beneficial, though it should always be implemented under the guidance of a nutritionist.

Medications may sometimes be prescribed for specific symptoms. For example, antispasmodics can alleviate abdominal pain, laxatives may relieve constipation, and anti-diarrhoeal agents can help manage loose stools. In cases of functional dyspepsia, acid suppressants may provide relief from upper abdominal discomfort.

Psychological therapies, such as cognitive behavioural therapy (CBT) or relaxation techniques, can also be highly effective in cases where anxiety or stress play a major role. Furthermore, these approaches can also help children and their families manage and cope with the impact of the disorder.

In some cases, probiotics may be another avenue of treatment, especially when dysbiosis is suspected. Certain strains of probiotics have been shown to help regulate gut microbiome balance and alleviate symptoms like bloating and irregular bowel movements, although their effectiveness can vary.

Education and reassurance are crucial throughout the treatment process. Parents often worry about their child’s symptoms; understanding that functional GI disorders are manageable can provide much-needed relief for both children and parents. Moreover, regular follow-ups with the paediatric gastroenterologist can help track progress and adjust treatments as needed.