Why the Name Change Matters
In 2016, the Rome Foundation officially recommended replacing the term "functional gastrointestinal disorders" with "Disorders of Gut-Brain Interaction" (DGBI). This was not a cosmetic rebrand. The word "functional" had become clinically counterproductive — patients heard "not real," doctors heard "psychosomatic," and insurance companies heard "not worth covering."
Surveys of both patients and clinicians confirmed the problem. Patients reported feeling dismissed, stigmatised, and frustrated when told their condition was "functional." Gastroenterologists admitted that they often spent less time and fewer resources on patients with functional diagnoses compared to those with structural pathology. The term had become a barrier to effective care.
The Bidirectional Axis
DGBI centres on the concept that these conditions arise from dysregulation along the gut-brain axis — a bidirectional communication system involving neural pathways (vagus nerve, spinal afferents), neuroendocrine signalling (serotonin, CRF, cortisol), immune mediators (mucosal mast cells, cytokines), and the gut microbiome. Dysfunction at any point along this axis — or at multiple points simultaneously — can produce the characteristic symptoms of altered motility, visceral hypersensitivity, and disordered central processing.
Critically, the model is bidirectional. Peripheral gut dysfunction (post-infectious inflammation, dysbiosis, impaired motility) can drive central symptoms (anxiety, hypervigilance, fatigue). Equally, central factors (psychological stress, trauma, catastrophising) can alter gut physiology through descending neural and hormonal pathways. Most patients have a mixture of both, and the relative contribution of peripheral vs central mechanisms varies between individuals and over time.
Psychogastroenterology
The DGBI framework has accelerated the emergence of psychogastroenterology — a subspecialty integrating GI medicine with psychological therapies. Gut-directed hypnotherapy, cognitive behavioural therapy for GI symptoms, acceptance and commitment therapy, and mindfulness-based stress reduction all have RCT evidence in DGBI, with effect sizes comparable to or exceeding pharmacotherapy.
The key insight driving this field is that psychological interventions for DGBI are not treating "the psychological cause" — they are modulating the central component of the gut-brain axis. A patient who improves with gut-directed hypnotherapy has not been shown to have a psychological disorder; they have responded to a central neuromodulatory intervention, just as a patient who improves with linaclotide has responded to a peripheral intervention.
Integrated Treatment Models
Best practice for DGBI is now moving toward integrated multidisciplinary care: dietary management (low-FODMAP, fibre optimisation), pharmacotherapy (neuromodulators, gut-specific drugs), psychological therapy, and exercise — tailored to the individual patient's predominant mechanisms. Single-modality treatment often produces incomplete responses because it addresses only one component of a multi-mechanism disorder.
The DGBI terminology is still gaining traction — many clinicians and patients continue to use IBS, functional dyspepsia, and functional constipation as more familiar labels. But the conceptual shift it represents — from "we can't find anything wrong" to "we understand the mechanism and can target it" — is transforming patient care.