A population-based study of familial coaggregation and shared genetic etiology of psychiatric and gastrointestinal disorders

It has been proposed that having a psychiatric disorder could increase the risk of developing a gastrointestinal disorder, and vice versa. The role of familial coaggregation and shared genetic loading between psychiatric and gastrointestinal disorders remains unclear. This study used the Taiwan National Health Insurance Research Database; 4,504,612 individuals born 1970–1999 with parental information, 51,664 same-sex twins, and 3,322,959 persons with full-sibling(s) were enrolled. Genotyping was available for 106,796 unrelated participants from the Taiwan Biobank. A logistic regression model was used to examine the associations of individual history, affected relatives, and polygenic risk scores (PRS) for schizophrenia (SCZ), bipolar disorder (BPD), major depressive disorder (MDD), and obsessive-compulsive disorder (OCD), with the risk of peptic ulcer disease (PUD), gastroesophageal reflux disease (GERD), irritable bowel syndrome (IBS), and inflammatory bowel disease (IBD), and vice versa. Here we show that parental psychiatric disorders are associated with gastrointestinal disorders. Full-siblings of psychiatric cases have an increased risk of gastrointestinal disorders except for SCZ/BPD and IBD; the magnitude of coaggregation is higher in same-sex twins than in full-siblings. The results of bidirectional analyses mostly remain unchanged. PRS for SCZ, MDD, and OCD are associated with IBS, PUD/GERD/IBS/IBD, and PUD/GERD/IBS, respectively. PRS for PUD, GERD, IBS, and IBD are associated with MDD, BPD/MDD, SCZ/BPD/MDD, and BPD, respectively. There is familial coaggregation and shared genetic etiology between psychiatric and gastrointestinal comorbidity. Individuals with psychiatric disorder-affected relatives or with higher genetic risk for psychiatric disorders should be monitored for gastrointestinal disorders, and vice versa. It has been proposed that people with psychiatric disorders such as depression could have an increased chance of developing gastrointestinal disorders such as irritable bowel syndrome. We looked at whether this was the case in a large number of people from Taiwan. We found that people with a psychiatric disorder, or with relatives having a psychiatric disorder, were more likely to have gastrointestinal disorders, and vice versa. These findings suggest that people who have psychiatric disorders or have psychiatric disorder-affected relatives should be monitored for gastrointestinal disorders, and vice versa, to enable them to benefit from all the treatments they might need to improve their health. Pan et al. examine whether there is a shared pathophysiological mechanism underlying brain-gut comorbidity. This population-based cohort and biobank study demonstrates that there is familial coaggregation and shared genetic etiology between psychiatric and gastrointestinal comorbidity.