Gut feelings: understanding the psychological drivers of persistent gastrointestinal complaints

A patient presents with abdominal pain, bloating, and altered bowel habits, yet clinical assessments and investigations return normal results. You diagnose irritable bowel syndrome (IBS) but the case feels more complex. The patient’s distress seems disproportionate to the clinical findings, symptoms are reported as severe and unrelenting, and there is a continued push for further investigations or referrals. These observations suggest an underlying interaction between gut symptoms and psychological functioning. Understanding this clinical picture requires considering how psychological factors may contribute to the persistence and severity of IBS symptoms.

What the Evidence Shows

Our recent article in Digestive Diseases explored this complex interplay, using a validated psychological assessment tool to investigate the relationship between personality, psychological distress, and gastrointestinal symptom reporting in a community sample. Findings confirmed that gastrointestinal disorders such as IBS are genuine and disabling, and frequently occur alongside psychological distress, somatisation, and certain personality traits.

In some individuals, gut related symptom reports were associated with emotional dysregulation, including suicidal ideation and validity indices suggest symptom overreporting. This level of distress was perceived as significant by the responder, and importantly not only impacted the way in which symptoms are related, but also the behavioural response to those symptoms.

Previous research has noted a prototypical ‘IBS personality’ characterised by higher levels of neuroticism (a tendency to experience negative emotion) and conscientiousness (a tendency towards self-control and responsibility), along with lower levels of agreeableness (pro-social tendencies) and openness (preference for new ideas and experiences) compared with the general population. Neuroticism, with its links to emotional reactivity, is particularly elevated in IBS, and may differ across IBS subtypes.

Such personality factors may result in a vulnerability to emotional distress manifesting as somatic symptoms and heightened awareness of gut sensations. These symptoms can increase emotional reactivity and the individual’s focus on their gastrointestinal discomfort. When investigations fail to find physical abnormalities, the necessary shift toward exploring psychological factors may be perceived by the patient as minimising or dismissing their symptoms. This perceived invalidation may further heighten distress, further reinforcing the cycle of symptom focus and emotional dysregulation.

How these psychological factors and gut physiology interact is increasingly explained by the gut–brain connection.

The Gut-Brain Connection

IBS is now classified as a disorder of gut-brain interaction (DGBI) (ICD-10 K59.9), involving dysregulation across the neuroendocrine, immune and gastrointestinal systems. Rather than only being a ‘stress-related’ condition, it involves a complex interplay of factors, including:

• heightened stress reactivity via the hypothalamic–pituitary–adrenal (HPA) axis;
• low-grade mucosal inflammation;
• microbiota imbalance; and
• increased intestinal permeability.

These processes are responsible for visceral hypersensitivity that may result in persistent gastrointestinal symptoms. Furthermore, personality factors, psychological distress, early life adversity and diet, further modulate this system.

Psychological Comorbidities Are Common

Patients with IBS frequently experience anxiety, depression, and trauma-related symptoms, all of which influence the gut-brain axis. The central nervous system (CNS) affects visceral sensitivity and motility, while the gut microbiome sends neuroimmune signals back to the CNS. Dysbiosis (imbalance of the gut microbiome) alters short-chain fatty acid (SCFA) production, tryptophan metabolism, and other pathways, impacting systemic inflammation, blood–brain barrier integrity, and CNS immune responses.

Implications for General Practice

IBS is highly prevalent with over 40% of adults and 12% of children experiencing a functional GI disorder at some point (here, here). The differential diagnoses are numerous and require clinical and investigational assessment, including:

• coeliac disease and other food intolerances including lactose intolerance;
• active and inactive inflammatory bowel disease, microscopic colitis, eosinophilic gastritis or enteritis;
• diverticulosis;
• colorectal cancer;
• medication-induced diarrhoea or constipation, post-cholecystectomy diarrhoea, laxative use;
• small intestinal bacterial overgrowth, bacterial gastroenteritis, post-infectious gastrointestinal motility disorders;
• hypothyroidism. Neuroendocrine tumour;
• endometriosis, gynaecological cancer and pelvic floor conditions; and
• psychiatric and personality disorders.

Patients with IBS are often concerned about the possibility of colorectal cancer which may present with similar (and often milder) symptoms. ‘Red flags’ for colorectal cancer include recent onset of symptoms without previous IBS symptoms, persistent change in bowel habit, rectal bleeding, and weight loss. A family history of colorectal cancer in first degree relatives should alert the clinician to the possibility of colorectal cancer.

Typical testing to consider includes:

• complete blood count;
• biochemical profile (including liver enzymes);
• iron studies;
• C-reactive protein;
• serologic markers for coeliac disease and tests for inflammation (for patients with diarrhoea predominance);
• faecal calprotectin; and
• measurement of thyroid-stimulating hormone and calcium levels (for patients with constipation).

Further Diagnosis and Management

When the clinical assessment indicates possible IBS, the GP could use several approaches to assist with diagnostic confirmation and further management:

1. Screen for psychological distress

Patients with chronic GI symptoms should be assessed for anxiety, depression, trauma history, and emotional dysregulation. Brief tools such as the PHQ-15, THS or DASS-21 can help identify these factors.

2. Focus on diagnostic clarity

Whilst patients may meet Rome IV criteria for IBS, recognising that distress and visceral sensitivity can intensify symptoms is important. Note symptom hypervigilance including constant monitoring, reassurance-seeking and food avoidance, and ask brief questions about stress and anticipatory anxiety. These psychological factors are part of the condition and should be considered when planning management. 

GPs can gauge distress and visceral hypersensitivity through listening to the language used to describe symptoms, through reactions to physical examination of the abdomen and pelvic cavity or using specific questionnaires such as the visceral sensitivity index (VSI) or the Gastrointestinal Symptom Rating Scale (GSRS).

Discuss why you consider more serious conditions such as IBD and colorectal cancer are unlikely and whether investigations to exclude these entities may or may not be needed. Such discussion is more likely to reassure the patient than cause distress. 

3. Be judicious with investigations. 

Investigations may inadvertently reinforce illness behaviours, prolonging distress and delaying recovery. A cautious, evidence-based approach is advised when assessing the differential possibilities.

While faecal calprotectin is a common, stool-based investigation, where elevations assist in the differential diagnosis of IBD, it may also be elevated with smoking, excessive alcohol use and with non-steroidal anti-inflammatory medications.

Sometimes it is necessary to recommend a colonoscopy or abdominopelvic imaging such as computed tomography (CT) or ultrasound (US) to exclude more serious pathology and to reassure a very anxious patient. In low risk patients, a practical alternative would be to review the patient in 4-6 weeks and only recommend such investigations if there has been no improvement in symptoms.

4. Refer to Clinical Psychology early

Psychological therapies such as trauma-informed cognitive behavioural therapy (a framework to acknowledging the impact of traumatic experiences on thoughts, feelings and behaviours) as well as other psychotherapies, address both symptoms, and importantly, their emotional drivers. These comprehensive approaches are likely to outperform gut-directed hypnotherapy, which tends to focus more narrowly on symptom relief.

5. Educate patients on the gut–brain axis

Simple explanations can empower patients, helping them understand how emotions and gut function interact.

6. Decision support

Using machine learning we have been able to identify distinct clinical research subgroups with MMPI-verified emotional dysregulation, cognitive disturbances, somatic and gastrointestinal complaints and suicidal ideation. These combined features may assist GPs in recognising patients with complex gut–brain presentations who require targeted intervention.

Conclusion

Understanding IBS and disorders of the gut-brain interactions as genuine biopsychosocial disorders rather than “medically unexplained symptoms” helps validate the patient’s experience. For GPs, acknowledging distress whilst recognising its impact on symptom-reporting, explaining gut–brain mechanisms and reassuring patients that care is appropriate can improve engagement and support coordinated, team-based management.

Dr Linda Thomas is a dual-qualified clinical psychologist and mucosal immunologist, bringing a combined clinician-researcher lens to the gut-brain-immune axis. As Director of  the specialty clinic 'Gut Feeling'  and Visiting Fellow at ANU, she translates this research into practical health care while also guiding medical student research exploring the gut-brain-immune connection.