Plate Nº 83 · recorded October 10, 2026
Health & Medicine ResearchReported finding
ADHD Linked to Nearly Double the Odds of Constipation in Study of 1.9 Million
A Warwick analysis of 23 studies covering 1.9 million people ties ADHD to ~50% higher odds of gut symptoms, with constipation odds nearly doubled.
By Marcus Bennett4 min read747 words
In brief
- Analysis of 23 studies covering more than 1.9 million people found ADHD linked to almost 50% higher odds of gastrointestinal symptoms.
- People with ADHD had nearly double the odds of constipation and over four times the odds of encopresis (loss of bowel control).
- Irritable bowel syndrome odds were 58% higher in people with ADHD.
- Published September 11, 2026, in the Journal of Attention Disorders; first systematic review of gut symptoms in ADHD.
- Findings show association, not causation; medications and gut microbiome differences are among possible explanations.
People with ADHD face nearly double the odds of constipation, 58% higher odds of irritable bowel syndrome, and more than four times the odds of encopresis — the loss of bowel control — according to a new analysis of data from more than 1.9 million people.
Overall, the University of Warwick researchers found that people with ADHD were almost 50% more likely to experience gastrointestinal symptoms than people without the condition. The team pooled results from 23 studies conducted in countries including the USA, Sweden, Germany and South Korea, with participants ranging in age from 2 to 65.
The study, published September 11, 2026, in the Journal of Attention Disorders, is the first systematic review devoted specifically to gastrointestinal symptoms in ADHD. Systematic reviews, which combine and analyze the results of many previous studies, are considered one of the strongest forms of medical evidence.
"Almost every gut symptom we looked at: constipation, IBS, even indigestion, appeared to be associated with ADHD," said co-lead author Sarah Blake, a medical student at Warwick Medical School. "These symptoms can have a real impact on daily life, but they could easily be overlooked if the focus is on ADHD itself."
Why hasn't this connection been clear until now?
ADHD is estimated to affect about 5% of children and 3-4% of adults worldwide, and reported diagnosis rates have risen sharply over the past four decades. Doctors have long documented digestive problems among people with autism spectrum disorder.
Scientists have also accumulated growing evidence for a "gut-brain axis" — a two-way communication system linking the digestive tract and the nervous system — that may connect digestive health with neurodevelopmental conditions more broadly. Until now, though, researchers had a far less complete picture of how often gastrointestinal symptoms appear in people with ADHD.
The new review begins to fill that gap by pulling together evidence from multiple countries and age groups into a single analysis.
What could explain the link?
The researchers stress that they do not yet know exactly why ADHD and digestive problems travel together. Several mechanisms could contribute.
- Behavioral traits. ADHD-related characteristics such as impulsivity and irregular eating patterns may influence digestive health.
- Medication side effects. Drugs used to treat ADHD can produce gastrointestinal side effects, including constipation.
- The gut microbiome. Previous research has linked ADHD with differences in gut bacteria. Those differences may affect communication between the digestive system and the brain via the vagus nerve, one of the body's major gut-brain pathways.
Crucially, the findings establish an association, not causation. The study cannot say whether ADHD itself leads to gut problems, whether shared biological factors underlie both, or whether medications and lifestyle factors account for part or all of the pattern.
"We can't yet say ADHD causes these gut problems, or exactly what is driving the link, but the pattern is striking enough to warrant attention," said Dr. Saran Shantikumar, associate clinical professor at Warwick Medical School. "Clinicians caring for people with ADHD may want to consider asking about gastrointestinal symptoms, particularly if they may be affecting quality of life."
What does this mean for patients and doctors?
The authors say clinicians who treat people with ADHD should stay alert to the possibility of gastrointestinal symptoms and consider asking patients about digestive problems during appointments. Blake notes these symptoms can easily go unnoticed when clinical attention centers on ADHD itself.
For patients experiencing more complicated gastrointestinal symptoms, the researchers suggest that support from a dietitian or a gastroenterologist — a specialist in digestive diseases — could be beneficial.
How strong are the findings, really?
The scale of the analysis is its main strength. Pooling more than 1.9 million participants across 23 studies gives the estimates far more statistical weight than any single study could provide.
But limitations remain. A pooled analysis can only be as reliable as the studies it draws from, and the review combines data from different countries, age groups and study designs. It also cannot disentangle the role of ADHD medications, which are known to cause constipation in some patients.
More research will be needed to determine how much of the connection reflects underlying biology and how much stems from medications or other influences. Until then, the practical takeaway for patients and clinicians is modest but concrete: digestive complaints appear common in ADHD, they can affect quality of life, and they deserve a direct question at the doctor's office rather than being lost in the shadow of the primary diagnosis.
via dx.doi.org (Original)
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