Inflammatory bowel disease (IBD) is a chronic gastrointestinal disorder resulting from genetic susceptibility, abnormal immune function in the intestinal mucosa, disruptions of gut microbiota, and other factors. With the population aging, the numbers of elderly patients with IBD and those with Alzheimer diseases (AD) are on the rise. Studies have demonstrated that there is a significant association between IBD and AD, as both conditions share similar pathophysiological mechanisms: immune imbalance, chronic inflammation and gut microbiota disruptions. This article reviews the comorbidity between IBD and AD and the common pathological mechanisms of these two conditions to provide reference for clinical management of these patients.