According to the Centers for Disease Control and Prevention, depression is a medical illness characterized by persistent sadness and sometimes irritability--particularly in children. Examples of depressive disorders include depression, major depression, dysthymia, and minor depression. There is no singular cause for depressive disorders. Instead, it is likely the result of a combination of genetic and environmental factors. It is often associated with higher risk for mortality from suicide and heart disease, lower workplace productivity and other illnesses such as anxiety disorders, substance abuse, and cancer. Not only can it interfere with an individual's daily functioning, but it can also have negative impacts on the communities they live in. According to the National Institute of Mental Health, major depressive disorder is the leading cause of disability for individuals ages 15-44 in the United States and affects nearly 14.8 million American adults, or about 6.7 percent of the adult population. Although many effective treatment options are available, many individuals who suffer from depression do not have access to treatment or do not seek treatment. Effective treatment for depression is important in order to prevent it from becoming a chronic disease.