First rank symptoms: concepts and diagnostic utility.

First Rank Symptoms (FRS) were first defined by Schneider as diagnostic of schizophrenia. Since then, there has been an immense debate on their diagnostic and prognostic utility. This review attempts to understand the concepts of FRS as depicted over the years and the diagnostic and prognostic implications of FRS in mental illnesses including schizophrenia. Review of relevant material showed that there are wide variations in the concepts of FRS which may be classified according to broad and narrow definitions. These variations have also led to the differences in the diagnostic systems currently being used. Although the diagnostic utility of FRS in schizophrenia remains, it is not clearly so with other mental illnesses in which these symptoms may also be observed. In addition there is controversy over the prognostic implications with evidence divided between poor and no influence on outcome.