Systematic Reviews
Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastrointest Pharmacol Ther. May 6, 2016; 7(2): 320-333
Published online May 6, 2016. doi: 10.4292/wjgpt.v7.i2.320
Neuroimaging the brain-gut axis in patients with irritable bowel syndrome
Kristen R Weaver, LeeAnne B Sherwin, Brian Walitt, Gail D’Eramo Melkus, Wendy A Henderson
Kristen R Weaver, LeeAnne B Sherwin, Wendy A Henderson, Digestive Disorders Unit, Biobehavioral Branch, Division of Intramural Research, National Institute of Nursing Research, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892, United States
Kristen R Weaver, Gail D’Eramo Melkus, College of Nursing, New York University, New York, NY 10010, United States
Brian Walitt, Division of Intramural Research, National Institute of Nursing Research, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892, United States
Author contributions: Weaver KR and Henderson WA participated in the conception and design; all authors contributed to data interpretation in addition to the drafts and revisions of the manuscript; all authors have approved the final version of the manuscript to be published.
Supported by Division of Intramural Research, National Institute of Nursing Research to W.A.H., No. 1ZIANR000018-01-05.
Conflict-of-interest statement: All of the authors have no potential conflicts of interest to disclose.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Dr. Wendy A Henderson, Digestive Disorders Unit, Biobehavioral Branch, Division of Intramural Research, National Institute of Nursing Research, National Institutes of Health, Department of Health and Human Services, 10 Center Drive, 2-1341, Bethesda, MD 20892, United States. hendersw@mail.nih.gov
Telephone: +1-301-4519534 Fax: +1-301-4801413
Received: May 9, 2015
Peer-review started: May 11, 2015
First decision: September 8, 2015
Revised: January 8, 2016
Accepted: February 23, 2016
Article in press: February 24, 2016
Published online: May 6, 2016
Processing time: 347 Days and 22.5 Hours
Abstract

AIM: To summarize and synthesize current literature on neuroimaging the brain-gut axis in patients with irritable bowel syndrome (IBS).

METHODS: A database search for relevant literature was conducted using PubMed, Scopus and Embase in February 2015. Date filters were applied from the year 2009 and onward, and studies were limited to those written in the English language and those performed upon human subjects. The initial search yielded 797 articles, out of which 38 were pulled for full text review and 27 were included for study analysis. Investigations were reviewed to determine study design, methodology and results, and data points were placed in tabular format to facilitate analysis of study findings across disparate investigations.

RESULTS: Analysis of study data resulted in the abstraction of four key themes: Neurohormonal differences, anatomic measurements of brain structure and connectivity, differences in functional responsiveness of the brain during rectal distention, and confounding/correlating patient factors. Studies in this review noted alterations of glutamate in the left hippocampus (HIPP), commonalities across IBS subjects in terms of brain oscillation patterns, cortical thickness/gray matter volume differences, and neuroanatomical regions with increased activation in patients with IBS: Anterior cingulate cortex, mid cingulate cortex, amygdala, anterior insula, posterior insula and prefrontal cortex. A striking finding among interventions was the substantial influence that patient variables (e.g., sex, psychological and disease related factors) had upon the identification of neuroanatomical differences in structure and connectivity.

CONCLUSION: The field of neuroimaging can provide insight into underlying physiological differences that distinguish patients with IBS from a healthy population.

Keywords: Irritable bowel syndrome; Neuroimaging; Brain-gut axis; Functional magnetic resonance imaging

Core tip: The present study reports replicable evidence that persons with irritable bowel syndrome have differences in brain structure and function when compared to healthy volunteers. Gender, psychological factors, and gastrointestinal symptom distress substantially influence these findings.