How long-term stress impacts the intestine  Premium

Chronic psychological strain and pressure can precipitate inflammation and dysmotility in the gut, details a recent study published in Cell journal

The crossroads of mental health and gastroenterology got a lot more attention in May this year, with a study published in Cell journal, titled ‘The enteric nervous system relays psychological stress to intestinal inflammation’. “Mental health profoundly impacts inflammatory responses in the body. This is particularly apparent in inflammatory bowel disease (IBD), in which psychological stress is associated with exacerbated disease flares,” it said, in summary.

“It’s an important study. What is excellent is that for the first time we have a much clearer understanding of the possible underlying mechanisms of inflammatory response and the whole cascade which ultimately precipitates the disorder. This is good not only for researchers but also for clinicians, because the pathways have been quite well explained,” says Sarath Gopalan, senior consultant paediatric gastroenterologist and hepatologist, Madhukar Rainbow Children’s Hospital, Delhi. In the future, he feels, with more research, drugs that block inflammatory cascades can be developed.

The study talks of stress pushing the adrenal gland to make glucocorticoids, a steroidal stress hormone. When stress is short-term, like before an exam, it may result in a loss of appetite and increased frequency of stools. When it’s chronic, or experienced long term, over a few weeks to months to years, like in a toxic job or marriage or through childhood with the pressure to perform, it can result in inflammation of the gastrointestinal tract, an example being inflammatory bowel disease (IBD).

With chronic stress, the body is constantly producing glucocorticoids. Two mechanisms may kick in, though the study does not describe whether both occur together or if there is a difference in the pace: “One is mediated by monocytes (white blood cells in the immune system that kill invaders) and TNF (tumour necrosis factor, a protein made by white blood cells), both mediators of inflammation through colony stimulating factor-1 (CSF-1, signalling pathways),” explains Gopalan. This results in physical changes to the intestine – damage to the intestinal mucous membrane due to the inflammation.

“The second is associated with neurotransmitter acetylcholine deficiency and dysmotility (abnormal speed of intestinal movement due to improper functioning of the muscles in the area). This is mediated through another inflammatory mediator: transforming growth factor (TGF) beta 2,” says Gopalan. This is the functional change in the gut.

IBD is quite different from irritable bowel syndrome (IBS) that is also precipitated by stress, and seen a great deal in women. Unlike IBD though, IBS does not cause, and neither is it caused by an inflammatory response. “If I do an endoscopy, a person with IBD will have physical changes to the colon; it may present like a wounded intestine – there may be ulcers for instance. There are morphological or structural changes. However, in IBS (characterised by bloating, constipation, diarrhoea) you won’t see any of that,” says Gopalan, adding that the IBD is caused by multiple factors, one of which is stress. “IBD is immunologically mediated (relating to the immune system) and can be hereditary.” Ulcerative colitis and Crohn’s disease are two examples of IBD and bear the risk of colorectal cancer, while IBS is a part of a larger clutch of disorders of the gut-brain interaction (DGBI).

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