NEGATIVE SYMPTOMS OF SCHIZOPHRENIA AND THEIR ASSESSMENT METHODS

The paper deals with the methodology and methods for the assessment of negative (or minus) symptoms of schizophrenia. Two approaches are distinguished: Rating scales and objective methods. Statistical analysis of symptom-ratings with comprehensive psychiatric assessment systems (eg Brief Psychiatric Rating Scale, Present State Examination) have supported the distinction between positive and negative symptoms. Therefore special scales have been constructed for the purpose of differentially assessing these symptoms, eg the Scale for the Assessment of Negative/Positive Symptoms (SANS, SAPS) or the Positive and Negative Syndrome Scale (PANSS). Relations to self-rating scales for subjectively experienced deficits and basic symptoms in schizophenic patients are pointed out, eg Frankfurt Complaint Inventory (FBFB) or Scale for Emotional Blunting (SEB). Psychometric properties of the rating scales for negative symptoms have to be improved, especially their validity often is not shown. Objective - rater-independent - assessment methods for negative symptoms are rare and being experimentally developed. Some symptoms may be assessed by psychological tests as deficiencies in psychological functioning, other by laboratory based (automated) analysis of behaviour, eg speech or facial actions. These investigations increase the reliability of the symptom-assessments. The validation of the methods involves etiological, prognostic and treatment implications of the negative symptoms. Current results suggest, that the negative syndrom of schizophrenia is a heterogenous construct, which has further to be differentiated.