A new study has uncovered a notable link between attention-deficit/hyperactivity disorder (ADHD) and a range of gastrointestinal (GI) symptoms. Researchers analyzed data from over 1.9 million people across 23 studies and found that individuals with ADHD were nearly 50% more likely to experience GI issues compared to those without ADHD. Specific conditions showed even stronger connections, such as a nearly doubled risk of constipation, a 58% higher chance of irritable bowel syndrome (IBS), and more than four times the risk of encopresis — a condition where stool leaks involuntarily. Published in the Journal of Attention Disorders, this study is the first systematic review to focus on GI symptoms in people with ADHD. The research included participants aged 2 to 65 from multiple countries, including the USA, Sweden, Germany, and South Korea. Co-lead author Sarah Blake, a medical student at Warwick Medical School, noted that nearly every GI symptom examined — including constipation, IBS, and indigestion — appeared to be connected to ADHD. These symptoms can significantly affect daily life but might be overlooked if attention is focused only on ADHD itself. Researchers have proposed several possible explanations for the connection. ADHD-related traits, such as impulsivity and irregular eating habits, may impact digestive health. Additionally, some ADHD medications are known to cause gastrointestinal side effects, including constipation. Another potential factor is the gut microbiome — the community of bacteria living in the digestive system — with earlier studies suggesting that people with ADHD may have different gut bacteria. These differences could influence communication between the gut and the brain via the vagus nerve, a key nerve involved in regulating bodily functions. The study underscores the importance of considering gastrointestinal symptoms in the care of individuals with ADHD. Healthcare providers may need to ask patients about digestive issues during appointments. Those with more severe or complex symptoms could benefit from guidance from a dietitian or a gastroenterologist, a specialist in digestive health. It is important to note that the study identifies an association, not a direct cause-and-effect relationship. More research is needed to understand how much biological factors, medications, or other influences contribute to the connection between ADHD and GI problems.