GENES may go some way towards explaining why a common but poorly understood gut disorder – irritable bowel syndrome (IBS) – is often linked to anxiety, say researchers.
They hope their discovery will stop IBS from being wrongly labelled as an emotional state or “all in the mind”.
The team studied more than 50,000 individuals with IBS, comparing their DNA with that of healthy people. The results are published in the journal Nature Genetics.
IBS is thought to affect about one in 10 people and can cause distressing abdominal pain, bloating and bouts of constipation, diarrhoea or both. With no defining test, diagnosis comes after ruling out other causes.
Women are slightly more affected than men, and the usual age for patients to seek advice is between 20 and 40.
Prof Miles Parkes, a consultant gastroenterologist at Cambridge’s Addenbrookes Hospital who led the gene research, says IBS is still poorly understood, even by some doctors, and may be incorrectly categorised as psychosomatic because of the overlap with anxiety and stress.
He and his team say they have identified at least six distinct genetic differences that might, at least partly, explain this link between the gut and the mind.
The results showed: Overall, heritability of IBS (how much your genes influence the likelihood of developing a particular condition) is quite low, Six genetic differences were more common in people with IBS than in controls, Most of these have roles in the brain, and possibly the nerves which supply the gut, rather than the gut itself, The same genetic make-up that puts people at increased risk of IBS also increases the risk for common mood and anxiety disorders such as anxiety, depression, and neuroticism, as well as insomnia and That doesn’t mean anxiety causes IBS symptoms or vice versa, says Prof Parkes.
“Our study shows these conditions have shared genetic origins, with the affected genes possibly leading to physical changes in brain or nerve cells that in turn cause symptoms in the brain and symptoms in the gut.”
The discovery might ultimately help with developing better tests and treatments for IBS.