Abstract
Patients with attention-deficit hyperactivity disorder (ADHD) reported significantly more constipation and flatulence than healthy controls. An altered gut microbiome can be associated with gastrointestinal symptoms. However, comprehensive information about associated risk of intestinal disorders and ADHD remains limited. A systematic review of the literature was therefore conducted to investigate the association between ADHD and different types of intestinal disorders. A total of 11 studies with 3,851,163 unique individuals, including 175 806 individuals with ADHD and 3 675 357 individuals without ADHD were included. The pooled OR of intestinal disorders for individuals with ADHD was 1.25 (95%CI, 0.75-2.07). A significant positive association was found between ADHD and irritable bowel syndrome (IBS) (OR 1.63 [95% CI 1.45-1.83]). Studies conducted in Eastern Mediterranean Region yielded a summary OR estimate that was higher than summary OR estimates in studies conducted in Region of the Americas, European Region and Western Pacific Region (3.03 [1.53-5.99] vs. 2.20 [1.05-4.63], 1.04 [0.44-2.41], 0.68 [0.25-1.87]), with p value 0.053, indicating a trend towards significance. High heterogeneity was observed. Our study supports association between ADHD and increased risk of IBS. Our study suggests an altered gut microbiome is the potential link that bridges gap between ADHD and intestinal disorder.