A review published in The American Journal of Gastroenterology examined the role and use of central neuromodulators in treating patients with irritable bowel syndrome (IBS).

IBS—a disorder of gut-brain interaction—is characterized by abdominal pain related to defecation and changes in stool frequency and form, often coexisting with psychiatric conditions such as depression and anxiety that can either precipitate or result from IBS symptoms.

Among the IBS subtypes are:

• IBS with constipation (IBS-C)
• IBS with diarrhea (IBS-D)
• IBS with mixed bowel habits (IBS-M)
• Unclassifiable IBS (IBS-U)

In the review, investigators delved into how central neuromodulators such as antidepressants, antianxiety drugs, and antipsychotics can be used to effectively manage IBS symptoms by regulating the gut-brain axis.

Central neuromodulators were found to enhance synaptic transmission of serotonin, noradrenalin, and dopamine. These agents regulated the gut-brain axis, impacting motility, secretion, and neural signaling. This regulation addressed psychiatric comorbidities, gut motility issues, visceral signal downregulation, and neurogenesis enhancement.

The investigators emphasized that the selection of central neuromodulators depended on the patient's predominant symptoms and bowel habits. For instance:

• Tricyclic Antidepressants were recommended for IBS pain and diarrhea, but may induce constipation
• Serotonin and noradrenaline reuptake inhibitors could be used as alternatives for pain management
• Selective serotonin reuptake inhibitors were recommended for anxiety and hypervigilance symptoms and may be beneficial for constipation, but may cause diarrhea.

The investigators revealed that a clinical response typically manifested within 6 to 8 weeks, with long-term treatment often necessary to prevent relapse. They noted that augmentation therapy, involving the addition of a second treatment such as atypical antipsychotics or gut-brain behavioral therapy, may have been beneficial if the primary treatment was only partially effective or induced side effects. Gradual tapering of central neuromodulators over at least 4 weeks was advised to minimize discontinuation effects.

IBS and other disorders of the gut-brain interaction involved gut-brain axis dysregulation. Neuromodulators targeted the gut-brain axis to normalize its functions, addressing visceral hypersensitivity, altering intestinal transit, and providing neurogenic effects. The gut-brain axis also interacted with the intestinal microbiota, contributing to the brain-gut-microbiota axis, which affected gut and brain health.

The investigators underscored that central neuromodulators may help manage both gut and psychiatric symptoms in patients with IBS. Although further studies may be needed to confirm the results of the study, the findings supported their efficacy in this patient population.