Psychiatry A Psychiatrist is a physician who specializes in the prevention, diagnosis and treatment of mental, addictive and emotional disorders, e.g. psychoses, depression, anxiety disorders, substance abuse disorders, developmental disabilities, sexual dysfunctions, adjustment reactions, etc. Psychiatrists understand the biological, psychological and social components of illness and are qualified to order diagnostic laboratory tests and to prescribe medications, as well as to evaluate and treat psychological and interpersonal problems. Psychiatrists are also prepared to intervene with individuals and families who are coping with stress crises and other problems of living.