Yes, it’s true, IBS does run in the family. You have more chance of having IBS if a parent or a sibling has it. And twins, especially identical twins have a particularly strong chance of both having IBS. But does that point to a genetic link? A recent large scale population study in Sweden showed that the association of IBS was not only greater in first degree relatives, but also in spouses, suggesting either the importance of shared environmental influences or an interpersonal identification rather than genetics1.
Although there is no specific gene for IBS, genetic studies have shown ‘polymorphisms’ in genes encoding for certain serotonin receptors or cytokines, though the significance of these is questionable2. There is also that intriguing association between double-jointedness and constipation in the family, which is probably related to a genetic defect in elastic tissue3. There may also be inheritance of a predisposition to allergy or ‘atopy’.
Nature and nurture always operate together. Genes may only be expressed if the environment is conducive. By environment, I don’t just mean the house or country they live in, but more important for IBS, the food they eat, the social environment, what is happening in their lives and the teeming populations of microbes that inhabit their guts.
There are several thousand times as many genes in the colonic microbiome than exist in our human genome, encoding several thousand more proteins and thousands more metabolic processes. Not only do the bacteria in our gut alter the expression of our human genes, but our environment, the food we eat, the rate it travels through the gut, the composition and amount of nutrient delivered to the colon, the changes in pH and redox potential, all influences the composition and expression of our microbiome. It’s an integrated system. People who live together not only eat the same food, they harbour the same bugs. The future, it seems, for ‘the IBS family’, is brown! .
But there’s more. IBS is an illness that expresses not so much pathology as meaning. Shock, trauma, severe anxiety, depression often goes to the gut, causing nausea and vomiting, abdominal pain and bowel upset. ‘You make me sick’, ‘Stop Bellyaching’ ‘It gives me the shits’ ‘Gut wrenching’ are among the many gut metaphors used to describe emotion
In a recent review of functional gastrointestinal disorders in childhood, a triggering event, either emotion or infection is identified in about 80% of children with functional gastrointestinal disorders4. Childhood is a time of drama, change and trauma. Trouble or separation in the family, being excluded from a peer group, feeling forced to do something that feels wrong, not being able to keep up, being teased or bullied, the pressure or examinations; all of these can assume enormous significance to a vulnerable child who may not have the confidence to handle them without becoming ill. Our conscious recollection of a particular upsetting event may fade with time, but the memory can linger on as the gut feeling, an emotional ember that is rekindled by association.
The family is the crucible of traumatic memory. It conditions the people we become. The abdominal symptoms caused by potty training, family disputes at meal times, or the painful death of a close relative from bowel cancer can remain etched in the nervous system as a record of what happened. Children who go on to develop IBS often suffer with anxiety and bowel dysfunction5. There is also evidence that severe stress/abuse in childhood can lead to epigenetic upregulation of glucocorticoid receptors that may predispose to IBS in later life.
Rory has always been a sensitive child and rather fussy with his food, but things were never as bad as they became last summer. He was having supper with his mother and stepfather who seemed cross with each other. He didn’t have any appetite and was just pushing his food around his plate, when his father shouted at him to eat it up. His mother shouted back, ‘Leave him alone’, whereupon Rory got severe stomach pains. Nevertheless his stepfather made him eat it. His pains became unbearable and he was sick and had diarrhoea, all over the living room floor. His stepfather swore and stormed out of the house, slamming the door. Three months later he left for good. Rory felt it was all his fault; he had made his father angry and his mother unhappy. Meal times always seemed to bring on his abdominal pain.
Children are often the lightening conductor for family strife. Marital dispute and breakdown can tear their whole identity apart and cause over dependency and debilitating illness. Neglected or overprotected children may never gain the confidence to manage the vicissitudes of everyday life without feeling ill. Children with recurrent abdominal pain are more likely to have parents who are anxious or depressed or have chronic ill health6. Having an ill parent predicted development of IBS6
Arguably, the most important thing that parents can offer their children is the confidence to take them for granted while they get on with the essential business of establishing their own identity and independence. Continued disruption can anchor the child to the dysfunctional family, undermining their confidence and leaving them to bear the family tension in their body and express it as illness.
Many adults with IBS report that their illness started early in life. Children tend to pick up the same behaviour as their parents and learn to react to stress with abdominal symptoms. Children of IBS patients tend to go to their doctors more frequently6 Studies reported in the nineteen seventies indicated that children with recurrent abdominal pain were abnormally anxious and sensitive and more of them went on to develop similar symptoms in adulthood7. and a more recent cohort study showed that such children were more likely to develop psychosomatic illness6.
But it’s not only trauma that may predispose to a familial tendency to IBS. Ideas and beliefs around food and illness are often shared within a family and implanted in childhood. If a parent avoids certain foods, the family will avoid them too, implanting the idea is implanted that those foods could make you ill. It is not often what is that troubles us, it’s the way we think it is, and this is so often conditioned by our upbringing,
Great post Nick
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