IBS and the gut-brain axis: why psychology isn't the whole story

What just happened

On 3 August, MJA InSight+ published a clinical commentary from a group including a dual-qualified clinical psychologist and mucosal immunologist from ANU, calling on GPs to rethink how they approach IBS — specifically, to screen for psychological comorbidities earlier and refer to clinical psychology sooner.

That sentence, for many patients, will land with a jolt. Because for many people with IBS, “we think there may be a psychological component” has been the thing that ends the conversation rather than advances it — the phrase that signals the doctor has run out of ideas and is now redirecting rather than listening.

The MJA commentary is asking something different. It is not suggesting the symptoms are imaginary. It is mapping a biological mechanism by which psychological factors directly alter gut function — and arguing that understanding this is part of understanding IBS, not a substitute for it.

That distinction matters enormously to the patient sitting in front of you.

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Both-and

IBS is a disorder of gut-brain interaction — which is a biological classification

The critical reframe in this article is the classification shift. IBS is now formally categorised as a disorder of gut-brain interaction (DGBI) — a recognition that the condition involves dysregulation across multiple systems simultaneously.

The gut-brain axis is a bidirectional communication network. Signals travel both ways: from the central nervous system to the gut (altering motility, secretion, and inflammation) and from the gut to the brain (via the enteric nervous system, the vagus nerve, the microbiome’s metabolic outputs, and neuroendocrine signalling). When stress activates the hypothalamic-pituitary-adrenal axis, it does not just affect mood — it directly alters gut function, increasing intestinal permeability, triggering low-grade mucosal inflammation, and amplifying visceral sensitivity.

Visceral hypersensitivity — the heightened perception of normal gut sensations as painful — is one of the core mechanisms in IBS. It is not a reporting artefact. It reflects measurable changes in the way the enteric nervous system processes sensation. Psychological distress does not create this, but it amplifies it substantially.

This is the reason psychological comorbidity in IBS is not incidental. Over 40% of adults experience a functional gastrointestinal disorder at some point, and IBS is particularly common in women — with anxiety, depression, and trauma-related symptoms frequently co-occurring. The relationship runs in both directions: psychological distress worsens gut symptoms, and gut symptoms worsen psychological distress. Treating one without addressing the other tends to produce incomplete results.

The personality framing — useful or reductive?

The MJA commentary describes a “prototypical IBS personality” characterised by higher neuroticism and conscientiousness, and lower agreeableness and openness compared with the general population. Neuroticism — a tendency toward emotional reactivity and negative affect — appears particularly elevated and may create vulnerability to the cycle of symptom focus and emotional amplification that can sustain IBS.

This framing deserves some careful handling. Personality profiles derived from population data describe statistical tendencies, not individual patients. “You have a high-neuroticism personality” is not a useful or appropriate clinical message for someone already dealing with dismissed, chronic gut symptoms. What the personality research points to clinically is a predisposition to visceral hypervigilance — a heightened monitoring of gut sensations that amplifies the signal — not a character flaw.

The more useful clinical translation is: in patients whose symptom reports seem disproportionate to clinical findings, or who display significant distress, reassurance-seeking, and persistent push for further investigation, it is worth considering whether visceral hypervigilance is part of the picture — and addressing that specifically, with validated tools like the Visceral Sensitivity Index.

The investigation trap

One of the most practically important observations in the article is the risk of over-investigation. The commentary notes that “investigations may inadvertently reinforce illness behaviours, prolonging distress and delaying recovery.” A judicious, evidence-based approach is recommended — reserving colonoscopy or abdominopelvic imaging for patients with red flags or very high anxiety, rather than as routine IBS workup.

Red flags that do warrant investigation: recent onset without prior IBS symptoms, persistent change in bowel habit, rectal bleeding, unexplained weight loss, family history of colorectal cancer in a first-degree relative. When red flags are absent, a structured 4–6 week review and symptom monitoring approach is often more appropriate than an escalating investigation ladder.

The parallel clinical message: explaining clearly to the patient why serious pathology is unlikely — and what features you would be watching for — is more likely to reassure than further investigation. Uncertainty breeds further investigation requests; clarity interrupts that cycle.

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My two cents

Here is the thing about the dismissal that IBS patients carry.

It is not usually a single bad encounter. It is the accumulation: the normal colonoscopy that produced a shrug, the “your bloods are fine” that meant “nothing to see here,” the suggestion that “stress” might be a factor offered without any mechanism or plan, in a way that felt like an ending rather than an opening.

The MJA commentary is asking GPs to do something genuinely different: offer the gut-brain mechanism as an explanation — not a redirection. That means naming the enteric nervous system. Naming visceral hypersensitivity. Naming why anxiety and gut function interact. Giving the patient a model of what is happening, rather than a list of what has been ruled out.

The clinical psychology referral, framed this way, becomes something different. Not “I don’t know what else to do” but “there is a specific mechanism here that psychological therapy directly addresses — and it is part of the full treatment picture.”

This requires more consultation time than most MBS item numbers support. It requires GPs to be comfortable with gut-brain explanations. And it requires the patient to have had enough experiences of being taken seriously to risk the phrase “psychological component” without immediately shutting down.

None of that is easy. But the article is right that the outcomes are better when it happens early — before the investigation ladder, before the reinforced illness behaviours, before the years of ongoing uncertainty.

Verdict: yes — the evidence for addressing psychological comorbidities as an integrated part of IBS management is solid, the mechanism is understood, and the framing shift this article advocates for is one that practitioners can implement now with tools already available. Worth reading in full.

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Sources cited

1. Thomas L, Lang P, Viljoen D, Lidbury B, Bassett M. Gut feelings: understanding the psychological drivers of persistent gastrointestinal complaints. MJA InSight+, 3 August 2026. https://insightplus.mja.com.au/2026/30/gut-feelings-understanding-the-psychological-drivers-of-persistent-gastrointestinal-complaints