A mental illness (emotional disability, cognitive dysfunction) refers to a group of illnesses that include emotional instability, behavioral dysregulation, or cognitive dysfunction.  Mental illnesses can result from biological (such as, chemical or genetic) or psychological (such as, trauma or conflict) reasons.  Mental illnesses can affect people at home, school, work or personal relationships.

Mental illnesses are treatable; treatments to assist with managing symptoms may include counseling, support groups and/or medication.  Any form of treatment should be managed by an appropriate health care professional.

Mental illnesses can affect people of different ages (children, adolescents and adults), race, religion, location or income status.  It is not induced by a personal weakness, lack of character or poor up-brining.

Some common mental illnesses that affect people include anxiety, ADHD, depression and anorexia.