A systematic review by the University of Warwick reveals that individuals with ADHD are substantially more likely to experience gastrointestinal issues, prompting calls for integrated clinical approaches.
New research from the University of Warwick suggests that attention deficit hyperactivity disorder is linked with substantially higher rates of digestive problems, adding to growing evidence that the gut and brain may influence one another in people with neurodevelopmental conditions. In a systematic review and meta-analysis published in the Journal of Attention Disorders, researchers examined data from more than 1.9 million people across 23 studies and found that those with ADHD had about a 50% higher rate of gastrointestinal symptoms than those without the condition.
The strongest associations were seen with constipation, irritable bowel syndrome and encopresis, a condition in which bowel control is lost. According to the Warwick team, the odds of constipation were nearly doubled, the likelihood of irritable bowel syndrome was 58% higher and the odds of encopresis were more than four times greater. The review drew on studies from the US, Sweden, Germany and South Korea and included participants aged two to 65.
Sarah Blake, a medical student at Warwick Medical School and co-lead author of the study, said the findings suggest many digestive symptoms may be missed if clinicians focus only on ADHD itself. The researchers said possible explanations include impulsive eating habits, irregular routines and side effects from ADHD medicines, which can include constipation. They also pointed to emerging evidence around differences in gut bacteria and the vagus nerve, which carries signals between the gut and brain.
The review builds on earlier research that has explored the gut-brain axis in ADHD, including studies suggesting that changes in gut microbiota and gut permeability could play a role in symptoms and behaviour. But the Warwick authors stressed that their findings show an association rather than proof that ADHD causes digestive illness. They said doctors treating children and adults with ADHD should consider asking about bowel and stomach symptoms, and refer patients with more complex problems to dietitians or gastroenterologists when needed. Saran Shantikumar, associate clinical professor at Warwick Medical School, said the pattern was strong enough to deserve attention, even though the underlying cause remains unclear.
Disclaimer: This content is for informational purposes only and is not intended to be a substitute for professional medical judgment, advice, diagnosis, or treatment.
