A March 2017 study1 considered the growing consensus that irritable bowel disease (IBD) is associated with anxiety- and depression-related symptoms. Being that diet is strongly related to both GI tract diseases and depression (the latter will be discussed in the next blog Gut Microbiota & Depression), it seems intuitively clear that changes to dietary intake could “kill two birds with one stone”.
Differences between Crohn’s disease (CD) and ulcerative colitis (UV)?
The authors of this study noted that the psychological symptoms of anxiety and depression are more apparent during active disease states. There was no difference recorded in prevalence between Crohn’s disease and ulcerative colitis.
Mechanisms at work
The likely mechanisms involved in the association between IBD and depression a concerned with communication between the gut and brain (the microbiota gut-brain axis). This is a close bidirectional relationship that includes neural, hormonal and immune communication links. Evidence exists for a number of interacting factors, including:
- the brain’s inflammatory response system
- the hypothalamic-pituitary-adrenal axis
- brain areas implicated in altered behaviours
- changes in blood-brain barrier integrity
- gut microbiota and responses to probiotics in IBD
What causes IBD to develop?
Opinions on psychological stress being a causal factor remain “somewhat conflicted”. However, the preponderance of evidence suggests that stress or early stressful life events are clear risk factors for developing IBD.
The authors recommended that; “…patients with IBD be screened for psychological disturbance and treated accordingly as intervention can improve quality of life and may reduce relapse rates.”
Irritable bowel syndrome (IBS) related to specific bacteria
A further May 2017 study2 found differences in gut microbes* between a group of IBS sufferers (the IBS group) and a group with no IBS (the control group). They discovered that microbes belonging to the genera Faecalibacterium, Blautia, and Bacteroides were present in significantly larger numbers in the IBS group than in the control group.
When personal histories were investigated, it became apparent that the above IBS group had a significantly higher incidence of early life trauma than the control group. They also found that gut microbial composition correlated with differences in brain structure, including sensory- and salience-related regions, as well as with the history of early life trauma.
They concluded that these results: “…confirm previous reports of gut microbiome-based IBS subgroups and identify for the first time brain structural alterations associated with these subgroups. They provide preliminary evidence for the involvement of specific microbes and their predicted metabolites in these correlations.”
*”Microbe” is a term generally used to mean anything small – this would include bacteria, but also yeasts, fungi and even protozoa. However, it usually does not include viruses.
An August 2017 study3 , which looked into how specific treatment with a probiotic bacteria called Bifidobacterium longum NCC3001 (BL) may be involved in the co-morbid conditions of IBS and depression/anxiety, concluded that: “In a placebo-controlled trial, we found that the probiotic BL reduces depression but not anxiety scores and increases quality of life in patients with IBS. These improvements were associated with changes in brain activation patterns that indicate that this probiotic reduces limbic reactivity.”
A March 2018 review4 considered the high level of co-morbidity of IBS and psychological states such as stress, hypersensitivity, anxiety, and depression. They looked at data linking dysbiosis in IBS with the presence of these clinical psychological states.
An April 2018 open-label observational study5 looked at the effects of faecal transplants on psychiatric symptoms among patients with IBS, functional diarrhoea and functional constipation. They concluded that: “Our results suggest that depression and anxiety symptoms may be improved by FMT regardless of gastrointestinal symptom change in patients with IBS, FDr and FC, and the increase of microbiota diversity may help to improve patient’s mood.”
The foregoing is just a small sample of the many studies in this field but, nevertheless, findings that link depression to intestinal diseases which generally are associated with a significant increase in the body’s inflammatory responses, make a lot of sense in light of other research findings that link inflammation to psychological conditions such as depression and anxiety. This will be covered in the forthcoming blog “Depression is Linked to Inflammation“.
- Gut-brain actions underlying comorbid anxiety and depression associated with inflammatory bowel disease. Abautret-Daly Á, Dempsey E, Parra-Blanco A, Medina C, Harkin A. Acta Neuropsychiatr. 2017 Mar 8:1-22. doi: 10.1017/neu.2017.3. PMID: 28270247.
- Differences in gut microbial composition correlate with regional brain volumes in irritable bowel syndrome. Labus JS, Hollister EB, Jacobs J, Kirbach K, Oezguen N, Gupta A, Acosta J, Luna RA, Aagaard K, Versalovic J, Savidge T, Hsiao E, Tillisch K, Mayer EA. Microbiome. 2017 May 1;5(1):49. doi: 10.1186/s40168-017-0260-z. PMID: 28457228.
- Probiotic Bifidobacterium longum NCC3001 Reduces Depression Scores and Alters Brain Activity: A Pilot Study in Patients With Irritable Bowel Syndrome. Pinto-Sanchez MI, Hall GB, Ghajar K, Nardelli A, Bolino C, Lau JT, Martin FP, Cominetti O, Welsh C, Rieder A, Traynor J, Gregory C, De Palma G, Pigrau M, Ford AC, Macri J, Berger B, Bergonzelli G, Surette MG, Collins SM, Moayyedi P, Bercik P. Gastroenterology. 2017 Aug;153(2):448-459.e8. doi: 10.1053/j.gastro.2017.05.003. Epub 2017 May 5. PMID: 28483500.
- Intestinal microbiome-gut-brain axis and irritable bowel syndrome. Moser G, Fournier C, Peter J. Wien Med Wochenschr. 2018 Mar;168(3-4):62-66. doi: 10.1007/s10354-017-0592-0. Epub 2017 Sep 8. Review. PMID: 28887729.
- The effect of fecal microbiota transplantation on psychiatric symptoms among patients with irritable bowel syndrome, functional diarrhea and functional constipation: An open-label observational study. Kurokawa S, Kishimoto T, Mizuno S, Masaoka T, Naganuma M, Liang KC, Kitazawa M, Nakashima M, Shindo C, Suda W, Hattori M, Kanai T, Mimura M. J Affect Disord. 2018 Apr 12;235:506-512. doi: 10.1016/j.jad.2018.04.038. PMID: 29684865.