Resting-state functional MRI activity and connectivity in inflammatory bowel disease: a systematic review

Area of Science:

• Neuroscience
• Gastroenterology
• Medical Imaging

Background:

• Inflammatory bowel disease (IBD), comprising Crohn's disease (CD) and ulcerative colitis (UC), extends beyond the gastrointestinal tract to affect the central nervous system (CNS).
• Resting-state functional MRI (rs-fMRI) is a valuable tool for investigating brain activity and functional connectivity.
• Understanding CNS involvement in IBD is crucial for a holistic patient approach.

Purpose of the Study:

• To systematically review and evaluate resting-state functional MRI (rs-fMRI) findings in patients with IBD.
• To compare rs-fMRI alterations in IBD patients with those in healthy controls.
• To identify potential differences in brain activity and connectivity between Crohn's disease (CD) and ulcerative colitis (UC).

Main Methods:

• Systematic literature search of PubMed/MEDLINE and SCOPUS databases.
• Inclusion of observational rs-fMRI studies focusing on neurologically asymptomatic IBD patients.
• Descriptive summary of findings based on rs-fMRI analysis techniques due to methodological heterogeneity.

Main Results:

• Twenty-seven studies were included, revealing varied rs-fMRI findings.
• Ulcerative colitis (UC) patients demonstrated reduced hippocampal activity and altered cerebellar/visual network connectivity, impacting memory and motor control.
• Crohn's disease (CD) patients showed increased activity in the anterior cingulate cortex and frontal regions, with altered connectivity in sensory and cognitive networks.
• Both CD and UC exhibited disruptions in default mode, salience, and cerebellar networks, linked to emotion, pain, and stress regulation.

Conclusions:

• Distinct rs-fMRI patterns differentiate UC and CD, with UC linked to decreased activity in memory/motor areas and CD to increased activity in emotion/cognitive regions.
• Shared disruptions in key brain networks highlight the pervasive impact of IBD on brain function.
• Findings underscore the significance of the brain-gut axis in mediating emotional and sensory impairments associated with IBD.