Psychiatry deals with prevention, assessment, diagnosis, treatment and rehabilitation of mental illness. A psychiatrist diagnoses and treats those with mental and emotional disorders such as schizophrenia, addictions, mood and anxiety disorders, substance-abuse disorders, and sexual and adjustment disorders. After assessment, the psychiatrist can diagnose, treat and manage an illness or problem by medication or various forms of psychotherapy. A psychiatrist is qualified to order diagnostic laboratory tests and to prescribe medications, evaluate and treat psychologic and interpersonal problems, and to intervene with families who are coping with stress, crises and other problems.