What is the branch of medicine concerned with the treatment of psychological disorders?

The branch of medicine that is concerned with the treatment of psychological disorders are psychology and psychiatry. Individual from psychology have PhD or PsyD doctoral degree and individual from psychiatry possess MD with four years of residency training in psychiatry. Person following psychology is called psychologist and can treat patient addressing behavioral patterns, but can't prescribe any medication. The person from psychiatry field is called psychiatrist and one who can prescribe medication and monitor patient.