Functional Gastrointestinal Disorders: Integrating Physiological and Psychological Approaches

By Dr. Priyom Bose, Ph.D.Reviewed by Danielle Ellis, B.Sc.

Symptoms and definition of FGID
Primary features of FGID
Physiological aspects of FGID
Phycological aspect of FGID
Clinical assessment of FGIDs
Integrative management of FGIDs
References
Further reading

Functional gastrointestinal disorders (FGID) are common disorders associated with persistent and recurrent gastrointestinal (GI) symptoms.¹ Several studies have indicated that stress and psychological difficulties make FGID worse. This article focuses on the physiological and psychological aspects of FGID.

Symptoms and definition of FGID

FGID occurs due to the abnormal functioning of the GI tract. A recent study indicated that around 40% of the world's population is affected by FGID.² In comparison to men, women are more commonly affected by FGID. Normally, the symptoms decrease with age. 

Several GI-related symptoms, such as dysphagia, bloating, abdominal pain, constipation, dyspepsia, and diarrhea, are grouped under FGID.³ Although previously FGID was defined as a condition with no organic basis, this definition has evolved with an increased understanding of this issue. As per the current definition, alterations in thebrain–gut communication could be the main mechanism behind the manifestations of FGID.⁴

The Rome Foundation originated in the late 1980s when not much information about the pathophysiology of FGIDs was available. This Foundation has played a vital role in operationalizing the research and circulating the knowledge regarding these disorders. The current ROME IV classification system of FGID categorized 33 adult disorders and 20 pediatric disorders.⁵

Irritable bowel syndrome (IBS) was found to be the most common form of FGID, followed by functional dyspepsia (FD). IBS causes abdominal discomfort, bloating, and altered bowel habits, whereas FD causes epigastric pain or discomfort.

Primary features of FGID

The three primary features of FGIDs are motility, sensation, and brain-gut dysfunction. Motility is associated with the muscular activity of the GI tract, which is basically a hollow, muscular tube. The normal motility of GI is peristalsis, which is a well-ordered sequence of muscular contractions starting at the top and ending at the bottom. An abnormal GI motility is present in patients with FGIDs. The muscular spasms of the GI tract, which could be very rapid, slow, or disorganized, cause the pain. 

The sensation depends on how the GI tract responds to stimuli, such as digesting a meal. In some cases, nerves linked to the GI tract are so sensitive that even normal muscular contractions can induce significant discomfort or pain. Disharmony in the brain-gut axis significantly affects the communication between the brain and the GI system. The regulator that keeps the brain-gut axis was found to be impaired in patients with FGID.⁶

Physiological aspects of FGID

Several abnormal physiological functions have been identified in people diagnosed with FGID, including low-grade immune infiltration, altered GI motility, gut microbial dysbiosis, and increased intestinal permeability. Furthermore, visceral hypersensitivity and altered central nervous system (CNS) processing of sensory input were found in patients with FGID.⁷

Gastroparesis is a motility disorder that occurs due to delayed gastric emptying. Some of the common symptoms associated with this condition are vomiting and nausea. Gastroparesis has been linked with abnormal gut neuronal morphology. Patients with IBS and FD exhibit the presence of inflammatory cells in the lamina propria of the gut and disturbed motility.

Phycological aspect of FGID

Several symptoms of anxiety are similar to FGIDs, including nausea, abdominal cramps, vomiting, and diarrhea. GI-specific anxiety is assessed using the visceral sensitivity index (VSI), which helps predict IBS symptom severity. Low mood or depression significantly contributes to GI symptoms.⁸

Even though FGIDs are not directly linked with eating disorders, the consumption of a specific meal linked to GI symptoms can lead to a disorder. In some cases, food phobias can occur due to a conditioned pairing of a specific food/meal with unpleasant GI symptoms.

Clinical assessment of FGIDs

Typically, FGID diagnosis involves a holistic approach where a detailed history of the patient, such as weight loss, anemia, nocturnal symptoms, family history of cancer, and GI bleeding, is considered. Clinicians ask about the diet, psychological status, and lifestyle. All this information is used to formulate an FGID management plan for the patient.

Physical examinations, including rectal examination, are performed to determine hemorrhoids and anal tone and function. Anal hypotonia could be a cause of constipation. Patients with IBS symptoms are subjected to blood and stool tests to determine the presence of Helicobacter pylori, C-reactive proteins, urea, electrolytes, and other biological markers. These patients are also subjected to endoscopy and abdominal ultrasound to determine the presence of anomalies.⁹

Integrative management of FGIDs

Due to the heterogeneity of FGID, it is difficult to design a treatment that fits all patients. A biopsychosocial approach has been designed that enables clinicians to identify the factors that trigger symptoms. Alteration of these triggering points could alleviate disease symptoms.

After FGID diagnosis, the bio-psycho-social factors are addressed to cure the condition. Proper lifestyle changes with a healthy diet, exercise, sleep, and limited consumption of caffeine and alcohol alleviate multiple FGID symptoms. In addition to lifestyle changes, psychological factors, such as stress, low mood, anxiety, and eating disorders, must be assessed and improved. Many pharmacological agents and psychotherapy have been found to be effective for FGID treatment.¹⁰

A recent meta-analysis has confirmed that psychological therapies, such as gut-directed hypnotherapy, Cognitive Behavioural Therapy (CBT), relaxation and mindfulness therapy, and dynamic psychotherapy, are effective for FGID. Among all psychotherapies, CBT is the easiest one to exhibit a significant reduction in FGID symptoms. It must be noted that the success of psychotherapy is dependent on the expertise of the therapist. Interestingly, the use of antidepressants has also shown effectiveness in IBS treatment. However, most antidepressants have GI side effects, such as constipation or diarrhea. 

The biological management of FGID involves the treatment of symptoms or underlying pathophysiology. In the case of symptomatic treatment, antiemetics are used to treat nausea, and laxatives for constipation. The use of opiates to relieve pain must be avoided as they may lead to the development of narcotic bowel syndrome that causes nausea, bloating, and constipation.

Antispasmodics are used to treat colicky abdominal pain in IBS. These pharmacological agents cause anticholinergic side effects of constipation and dryness of the eyes. Considering the side effects, it is important to choose pharmacological agents or antidepressants wisely to alleviate FGID symptoms.

References

• Black CJ. et al. Functional gastrointestinal disorders: advances in understanding and management. Lancet. 2020; 396(10263), 1664–1674. https://doi.org/10.1016/S0140-6736(20)32115-2
• Sperber AD. et al. Worldwide Prevalence and Burden of Functional Gastrointestinal Disorders, Results of Rome Foundation Global Study. Gastroenterology. 2021; 160(1), 99-114.e3. https://doi.org/10.1053/j.gastro.2020.04.014
• Fikree A, and Byrne P. Management of functional gastrointestinal disorders. Clinical Medicine. 2021; 21(1), 44-52. https://doi.org/10.7861/clinmed.2020-0980
• Mukhtar K, Nawaz H, and Abid, S. Functional gastrointestinal disorders and gut-brain axis: What does the future hold? World J Gastroenterol. 2019; 25(5), 552-566. https://doi.org/10.3748/wjg.v25.i5.552
• Schmulson MJ and Drossman DA. What Is New in Rome IV. J Neurogastroenterol and Motil. 2017; 23(2), 151-163. https://doi.org/10.5056/jnm16214
• What are FGIDs? https://www.med.unc.edu/ibs/patient-education/what-are-fgimds. 2023; Assessed on January 5, 2023.
• Burns GL, Hoedt EC, Walker MM, Talley NJ and Keely S. Physiological mechanisms of unexplained (functional) gastrointestinal disorders. Physiol J. 2021; 599(23), 5141–5161. https://doi.org/10.1113/JP281620
• Wu JC. Psychological Co-morbidity in Functional Gastrointestinal Disorders: Epidemiology, Mechanisms and Management. J Neurogastroenterol and Motil. 2012; 18(1), 13-18. https://doi.org/10.5056/jnm.2012.18.1.13
• Trivić I and Hojsak I. Initial Diagnosis of Functional Gastrointestinal Disorders in Children Increases a Chance for Resolution of Symptoms. PGHN. 2018; 21(4), 264-270. https://doi.org/10.5223/pghn.2018.21.4.264
• Bray N A. et al. Evaluation of a Multidisciplinary Integrated Treatment Approach Versus Standard Model of Care for Functional Gastrointestinal Disorders (FGIDS): A Matched Cohort Study. Dig. Dis. Sci. 2022; 67(12), 5593-5601. https://doi.org/10.1007/s10620-022-07464-1

Further Reading

• All Irritable Bowel Syndrome Content
• What is Irritable Bowel Syndrome (IBS)?
• Irritable Bowel Syndrome (IBS) Symptoms
• Irritable Bowel Syndrome (IBS) Causes
• Irritable Bowel Syndrome (IBS) Diagnosis