Abstract
Previous observational studies have suggested that higher levels of education attainment and intelligence (IQ) are associated with better health outcomes in humans. However, the causal link between education attainment and IQ and their association with health outcomes remains unclear. This study aims to investigate the distinct impacts of intelligence and educational attainment on gastrointestinal symptoms. From the genome-wide association between educational attainment and the IQ study database, results were obtained from the FinnGen summary database. We used univariate and multivariate Mendelian randomization (MR) techniques to explore the relationship between exposures and outcomes. To assess the validity of inverse-variance-weighted-based results, we used several supplementary analytical techniques and performed sensitivity analysis. Our multivariate MR study confirmed the findings from univariable analyses and showed a genetically predicted causal association between educational attainment and 8 gastrointestinal disorders, including gastroesophageal reflux disease, chronic gastritis, gastroduodenal ulcer, cirrhosis, cholelithiasis, acute pancreatitis, chronic pancreatitis, and irritable bowel syndrome. Our univariate MR study found an association between IQ and 6 gastrointestinal conditions: gastroesophageal reflux disease, cirrhosis, cholelithiasis, acute pancreatitis, pancreatic malignancy, and irritable bowel syndrome. However, the connection was much weaker in multivariate MR analysis. Our study revealed causal relationships between gastrointestinal disorders and educational attainment. Educational attainment may mediate between intelligence and the impacts on the gastrointestinal system. However, further research is required to understand the underlying pathogenic processes completely.