Clinical picture, pathogenesis and psychometric assessment of negative symptoms of schizophrenia.

Negative symptoms of schizophrenia constitute a serious diagnostic and therapeutic problem. They substantially account for the impairment of health, social functioning and quality of life whereas treatment is difficult. In this paper the development of the concept of schizophrenia and negative symptoms is presented. The models of positive and negative symptoms, introduced in the 1980's by Timothy Crow and Nancy Andreasen, and William Carpenter's concept of so-called deficit syndrome with the criteria of the division of negative symptoms into the primary and secondary, are discussed. Current views on the pathogenesis of negative symptoms are shown with reference to neuroimaging studies, neurotransmitter alterations, neuropsychological deficits, genetic, immunological and epidemiological studies. A subsection is devoted to the diagnostics tools for negative symptoms. Chronologically, they are divided into scales of the 1st and 2nd generation. The first generation includes: the Brief Psychiatric Rating Scale (BPRS), the Scale for the Assessment of Negative Symptoms (SANS), the Positive and Negative Syndrome Scale (PANSS), the Schedule for the Deficit Syndrome (SDS), and the Proxy for Deficit Syndrome. The second generation scales, developed as a result of the recommendation by American experts in 2006, include: the Brief Negative Syndrome Scale (BNSS) and the Clinical Assessment Interview for Negative Symptoms (CAINS), also the self-assessment scales: the Motivation and Pleasure Scale - Self Report (MAP-SR) and the Self-assessment of Negative Symptoms (SNS). The BNSS and the SNS scales, whose Polish versions were elaborated in the Department of Adult Psychiatry of Poznan University of Medical Sciences, are discussed in-depth.