Prospective investigations of the prodromal state of schizophrenia: assessment instruments

To review assessment instruments used for detection of prodromal or at-risk mental states, and discuss their role in current research.

A systematic electronic literature search was conducted and supplemented by a manual search. All relevant scales were selected for the purpose of the review.

Six interviews and four screening instruments were found. Two main traditions are prevailing: the Attenuated Positive Symptoms approach and the Basic Symptoms approach. Reports of psychometric properties of the interviews are preliminary.

The instruments detect individuals with an increased risk of psychosis in clinical populations, but predictive validity and measures of reliability is insufficiently evaluated. Studies including instruments from both traditions should be conducted, in order to obtain an empirical basis of hypothesized relations between instruments. Instruments elucidating phenomenological aspects of anomalies in self-experience may contribute with valuable data on the pre-onset phase of psychosis.