Mental health (psychiatric or psychologic) disorders involve disturbances in thinking, emotion, and/or behavior. Small disturbances in these aspects of life are common, but when such disturbances distress the person greatly and/or interfere with daily life, they are considered mental illness or a mental health disorder. The effects of mental illness may be long-lasting or temporary. These disorders are caused by complex interactions between physical, psychologic, social, cultural, and hereditary influences.

Last full review/revision December 2012 by Caroline Carney Doebbeling, MD, MSc