Three common types of mental disorders include anxiety disorders such as generalized anxiety disorder and panic disorder, mood disorders such as depression and bipolar disorder, and eating disorders such as anorexia nervosa or bulimia nervosa, according to WebMD. These types of disorders, among others, are recognized as mental illnesses.
People with anxiety disorders respond to certain situations with disruptive feelings of dread or fear and sometimes physical signs such as rapid heartbeats and sweating, WebMD explains. People with mood disorders, also called affective disorders, can experience continual feelings of sadness, extreme elation or fluctuations between the two. People with eating disorders experience extreme emotional and behavioral responses to food and body weight.