Disorders of the gut-brain interaction

Disorders of the gut-brain axis encompass a range of digestive conditions in which the sensitivity, motility and regulation of the digestive system may be impaired. Their symptoms are highly varied and can have a significant impact on eating, sleep and daily life.

What are gut-brain interaction disorders?

The gut and the brain maintain continuous, two-way communication via what is known as the gut-brain axis. This network involves the nervous system of the digestive tract, the brain and the spinal cord, as well as hormonal and immune signals and other mechanisms related to the gut environment.

Gut-brain axis disorders occur when one or more of these mechanisms function differently. As a result, the digestive system may become more sensitive to normal stimuli, alter its motility or process signals relating to digestion, the presence of food, gas or bowel movements differently. This can lead to pain, bloating, nausea, a feeling of fullness, diarrhoea, constipation or other digestive discomfort.

This is the scientific term currently used for a group of disorders that for many years were known as functional gastrointestinal disorders or functional digestive disorders. These terms may still appear in medical reports, publications and health-related content, but the current term better reflects our understanding of the biological mechanisms involved and the communication between the digestive system and the nervous system.

In lay terms, the term ‘gut-brain axis disorders’ may also be encountered. It refers to the same group of problems, although the standard medical term is ‘gut-brain interaction disorders’.

These disorders do not constitute a single disease. They include various clinical conditions, such as irritable bowel syndrome, functional dyspepsia and other disorders related to bowel movement, bloating, nausea, vomiting or bowel movements. Each has its own characteristics and requires an assessment tailored to each individual’s pattern of symptoms.

Which disorders form part of this group

Gut-brain interaction disorders can affect different areas and functions of the digestive system. They do not constitute a single disease, but rather a family of disorders with their own characteristics and diagnostic criteria.

Among the best known are irritable bowel syndrome, functional dyspepsia, functional constipation, functional diarrhoea and certain disorders related to abdominal distension, nausea, vomiting, the oesophagus or bowel movements. The Rome International Classification organises these disorders according to the area of the digestive tract affected and the predominant pattern of symptoms.

A single person may exhibit characteristics of more than one of these disorders. Consequently, the diagnosis aims to identify which symptoms predominate and which mechanisms may be contributing in each case, rather than applying a single explanation or treatment to all patients.

Causes and associated mechanisms

There is no single mechanism responsible for all disorders of gut-brain interaction. Current research links them to various combinations of alterations in visceral sensitivity, digestive motility, mucosal and immune system function, the gut microbiota, and the way in which the nervous system processes signals from the digestive system.

One of the most widely studied mechanisms is visceral hypersensitivity. In this condition, normal digestive stimuli — such as moderate distension, gas or certain bowel movements — can cause a sensation of pain or discomfort that is more intense than expected.

There may also be abnormalities in motility, that is, in the way the digestive tract contracts and moves its contents. Depending on the affected section and the type of abnormality, symptoms such as diarrhoea, constipation, a feeling of fullness after eating, difficulty passing stools or other symptoms may occur.

In some people, the onset of symptoms may follow a gastrointestinal infection. Individual predisposition, certain immune mechanisms, sleep, hormonal factors and physical or emotional experiences that influence the regulation of the gut-brain axis may also play a role. The link between acute gastroenteritis and the subsequent onset of some of these disorders is well documented.

The gut microbiota, comprising the microorganisms that primarily inhabit the gut, represents another important area of research. Its composition and activity may be linked to digestive, immune and metabolic functions, although at present its clinical assessment must be interpreted within the context of each individual’s overall symptoms and findings.

The role of stress and emotions

The brain and the digestive system maintain two-way communication. For this reason, stressful situations, sleep disturbances or certain emotional states can alter digestive sensitivity and the perception of symptoms.

In turn, living with pain, bowel urgency, nausea or dietary restrictions for months or years can affect sleep, mood and social life. This relationship works both ways and helps to explain why some therapeutic strategies act on the gut itself, whilst others target the mechanisms that regulate communication between the digestive and nervous systems.

Symptoms

Symptoms depend on the type of disorder and the part of the digestive system that is primarily affected. They may include abdominal pain or discomfort, bloating, visible distension, diarrhoea, constipation, an urgent need to pass stools, or a feeling of incomplete evacuation.

When symptoms mainly originate in the upper digestive tract, nausea, a feeling of becoming full too quickly, a sensation of fullness after eating, or pain and a burning sensation in the upper abdomen may predominate.

Symptoms tend to fluctuate. It is common to experience periods of greater stability and others of increased severity linked to meals, gastrointestinal infections, changes in sleep patterns, the menstrual cycle or certain stressful situations.

Some people also experience fatigue, sleep disturbances, headaches, muscle pain, anxiety or mood swings. The co-occurrence of several symptoms can contribute to the complexity of these disorders and must be assessed within the context of the overall clinical picture.

Symptoms requiring specific assessment

Unintentional weight loss, the presence of blood in the stools, anaemia of unknown cause, fever, persistent vomiting or progressive difficulty swallowing require investigation into other possible causes of the symptoms.

A family history of gastrointestinal cancer, inflammatory bowel disease or coeliac disease is also significant, as is the recent and progressive onset of certain symptoms. These factors help the specialist to decide whether further investigation is warranted and which tests may provide useful information.

Diagnosis

Diagnosis begins with a detailed medical history. The specialist assesses which symptoms are present, how long they have been present, how frequently they occur, their relationship to meals or bowel movements, possible triggers, and the impact they have on daily life.

The Rome criteria, an international framework developed specifically to recognise and classify gut-brain interaction disorders, are currently in use. In 2026, Rome V updated this system with clinical criteria designed to facilitate a positive diagnosis and adapted to clinical practice.

Following this initial assessment, the investigation is tailored to the pattern of symptoms, the patient’s age, medical history and clinical findings. Blood or stool tests may be requested to investigate, for example, anaemia, inflammation, coeliac disease, infection or other conditions that may cause similar symptoms.

Endoscopy and other gastrointestinal tests

When symptoms or initial results make it necessary to examine a specific area of the digestive tract directly, tests such as gastroscopy or colonoscopy may be used. These procedures allow the mucosa to be examined and biopsies to be taken where indicated.

In other cases, the clinical presentation may require different tests. Motility studies and manometry allow analysis of how a specific part of the digestive tract moves and functions, whilst certain bowel function tests help to investigate difficulties related to defecation.

Breath tests may be used when a specific clinical suspicion needs to be investigated, relating, for example, to the digestion or absorption of certain carbohydrates.

In this way, the investigation proceeds step by step: first, the clinical pattern is identified, and then the tests capable of answering the questions that have arisen during the assessment are selected.

Treatment

Treatment is tailored to the specific disorder, the predominant symptom and the impact that the symptoms have on daily life. As different mechanisms may be involved, management usually combines several strategies selected on a step-by-step basis. The Roma Foundation describes a multimodal and personalised approach to these disorders.

Understanding the diagnosis is an important part of treatment. Knowing which mechanisms may explain the pain, bloating, nausea or bowel disturbances makes it easier to set realistic goals and to understand why different people may require different treatments.

Diet and habits

Diet is tailored to the pattern of symptoms and individual tolerance. For some people, it may be helpful to adjust the size or timing of meals, modify fibre intake, or identify foods that consistently trigger symptoms.

For some patients with irritable bowel syndrome, a low-FODMAP diet may be considered. FODMAPs are certain short-chain carbohydrates that are poorly absorbed in the small intestine and can ferment once they reach the colon. They are found, in varying amounts, in some dairy products, fruit, vegetables, pulses and cereals.

When this approach is recommended, it is followed for a limited period, after which foods are gradually reintroduced to determine which types and quantities each individual can tolerate. The ultimate aim is to maintain as varied and balanced a diet as possible.

Regular physical activity, adequate sleep patterns and consistent bowel habits may also form part of the approach, always tailored to the individual’s situation and predominant symptoms.

Medicines

Medicines are selected according to the type of disorder and the problem to be managed. Treatments may be used to address constipation, diarrhoea, abdominal pain, nausea, a feeling of fullness or other specific symptoms.

In certain individuals, neuromodulators are used; these are medicines that alter the way the nervous system processes certain digestive signals and visceral pain. Some belong to families of drugs also used to treat mood disorders, but in this context they may be used specifically for their effect on sensitivity and gut-brain communication.

Probiotics constitute a highly diverse group of products. Their potential benefit depends on the strain, the formulation, the disorder and the symptom being treated; therefore, their use must be assessed on a case-by-case basis.

Treatments targeting the gut-brain axis

Some people may benefit from interventions specifically designed to modify the regulation of gut-brain communication. These include cognitive-behavioural therapy targeting digestive symptoms and gut-focused hypnotherapy, strategies that are recognised therapeutic options for certain disorders in this group.

These interventions focus on the way the nervous system processes digestive signals, the attention directed towards symptoms, and certain responses associated with pain or urgency. They may be combined with dietary or pharmacological measures where an individual’s specific circumstances warrant it.

Progression and monitoring

Gut-brain interaction disorders tend to have a chronic or recurrent course, with periods of varying intensity. Furthermore, the same person may experience changes in their predominant pattern of symptoms over time.

Their main impact may be on quality of life. Pain, bowel urgency, nausea, difficulty eating normally or the need to find a toilet can interfere with work, rest, travel and social relationships.

Regular follow-up allows us to monitor how symptoms are progressing and to assess which treatments continue to be beneficial. It also helps to gradually expand the diet once dietary changes have been made, to adjust medication and to reassess the situation if a pattern different from the usual one emerges.

The aim of long-term treatment is to reduce the frequency and severity of symptoms and ensure that they have an increasingly smaller impact on daily activities.

Specialists involved

The care pathway for gut-brain interaction disorders depends on the type of symptoms, their duration and the complexity of each case. Some people mainly require a clinical assessment and adjustments to their treatment, whilst others need gastrointestinal tests, nutritional intervention or specific strategies targeting the gut-brain axis.

At the Publio Cordón Memorial Hospital, the Digestive System Department is the centre of excellence for the assessment of these conditions. Within this speciality, the hospital has a Gut-Brain Axis Disorders Unit specifically dedicated to the diagnosis and management of complex functional digestive disorders, including irritable bowel syndrome and functional dyspepsia.

The first stage usually focuses on understanding the pattern of symptoms and determining which disorder might explain them. Based on this assessment, the specialist decides which tests or investigations may provide relevant information and how to organise treatment.

When it is necessary to examine the digestive tract directly via a gastroscopy or a colonoscopy, the Digestive Endoscopy Unit, which is also part of the Digestive System Department, may be involved.

Clinical gastrointestinal nutrition can be particularly important when symptoms are related to diet, where there are significant dietary restrictions, or where a structured dietary intervention is being considered. The hospital’s Gut-Brain Axis Disorders Unit includes professionals specialising specifically in clinical gastrointestinal nutrition, irritable bowel syndrome and the gut microbiota, which facilitates the integration of dietary management within the same care pathway.

For certain patients, it may be advisable to involve professionals with experience in psychological therapies specifically aimed at digestive disorders. Where there is also a specific mental health indication, the Publio Cordón Memorial Hospital has specialists in psychology and psychiatry. Their involvement is determined according to each individual’s needs and is not an automatic part of the digestive treatment pathway.

The care pathway is therefore developed progressively. It may begin with a gastroenterological assessment and continue, depending on the findings, with endoscopic or functional investigations, nutritional intervention or other therapeutic strategies. The aim is for each professional to be involved at the point when their intervention can provide information or improve symptom management.

Living with a gut-brain interaction disorder

Living with digestive symptoms that vary in intensity can affect mealtimes, travel, work or social life. Understanding the nature of the disorder and having a strategy to manage it helps to reduce uncertainty and gradually resume activities that had previously been restricted.

Recognising personal patterns can be useful for anticipating certain situations and adapting treatment. This self-monitoring should serve to deepen your understanding of your own symptoms, not to make food or digestive sensations the constant focus of your daily life.

Where dietary restrictions have been introduced, one of the aims of follow-up care is to restore a sufficiently varied diet. Similarly, medication and other interventions can be reviewed as symptoms and needs change.

Long-term management aims to ensure that symptoms are less frequent, intense or unpredictable, and that they interfere less and less with personal, family and professional activities.

Medical information for general guidance

The purpose of this content is to facilitate understanding of gut-brain interaction disorders, the mechanisms that may be involved in their onset, their various forms of presentation, and the options available for investigating and treating them. It also aims to help explain why the diagnostic and therapeutic pathway may differ depending on the predominant symptoms and the individual characteristics of each person.

At the Publio Cordón Memorial Hospital, we believe it is important for medical information to be accurate, understandable and useful in guiding each individual through their care journey. Our specialists devote part of their work to explaining conditions, tests and treatment options in an accessible way, helping patients and their families to better understand each stage and participate with greater confidence in decisions about their health. This commitment to knowledge and public outreach is also part of our dedication to research and the advancement of medicine.

The information provided in this factsheet is general in nature and cannot be used to establish a diagnosis or select an individual treatment. A medical assessment must take into account the pattern and progression of symptoms, medical history, physical examination and, where indicated, additional tests specific to each individual.

In the event of severe symptoms, those that appear suddenly, or those consistent with a possible medical emergency, a proper medical assessment is required.