To confirm the psychiatric diagnoses, case subjects were interviewed by trained clinicians using a structured psychiatric interview instrument, the Diagnostic Interview for Psychosis and Affective Disorder (DI-PAD). The DI-PAD is based on the Diagnostic Interview for Genetic Studies (DIGS24) and includes 90 phenomenological symptom items that are used with the Operational Criteria Checklist (OPCRIT) computer algorithm 25 to arrive at diagnoses using Diagnostic and Statistical Manual of Mental Disorders (DSM)26). Clinicians confirmed diagnoses for schizophrenia, schizoaffective disorder, or bipolar disorder with psychosis based on DSM-IV criteria.
