e., active-phase symptoms) and may consist of episodes of prodromal or residual symptoms. During these prodromal or residual periods, the signs of the disturbance may be demonstrated by only negative symptoms or by two or more symptoms listed in Criterion A present in a diminished form (e.g., odd beliefs, unusual perceptual experiences). Individuals who had been socially active may become remote from previous routines. Such behaviours are often the first sign of a disorder. Furthermore, mood symptoms and full mood incidences are common in schizophrenia and may be contemporary with active-phase symptomatology. However, as distinct from a psychotic mood disorder, a schizophrenia diagnosis involves the manifestation of delusions or hallucinations in the absence of mood episodes. In addition, mood episodes, taken in total, should be present for only a minority of the total duration of the active and residual periods of the illness. In addition to the five symptom domain areas identified earlier, the assessment of cognition, depression, and mania symptom domains is vital for making critically important differences between the various schizophrenia spectrum and other psychotic disorders. (DSM-V APA, 2013).
A range of standardized tests and interviewing instruments have been established to support in diagnosing of schizophrenia and evaluate the degree of symptom severity (Andreasen, 1991, Andreasen & Flaum, 1991). The most widely used tools were the Brief Psychiatric Rating Scale, the Scale for Assessing Positive Symptoms and Scale for Assessing Negative Symptoms (SANS). The development of The Present State Examination combined Schneiderian first-rank symptoms which directly influenced the development of the Schedule for Affective Disorders and Schizophrenia (SADS), the Positive and Negative Symptom Scale (PANSS), (Andreasen & Carpenter, 1993), and subsequently the Clinician-Rated Dimensions of Psychosis Symptom Severity (DSM-V APA, 2013).