A variety of illnesses are bidirectionally associated with depression. That association increases in people who have multiple diseases. Some diseases such as hypertension, cardiovascular disease, cancer, obesity, and diabetes are more highly associated. The most common co-occurring disease in adults is depression. Depression is two to three times more likely to occur in individuals with multimorbidity than in those without comorbidities or chronic medical conditions. Depression is associated with engaging in unhealthy behaviors, including overeating, regular smoking, alcohol use, and lack of exercise.