[Scale for assessing negative symptoms in schizophrenia: A systematic review]

Negative symptoms are a fundamental dimension of schizophrenia despite their limited role in the international diagnostic classification. Although a consensual definition seems to be attempted regarding the main negative dimensions (anhedonia, alogia, social withdrawal, blunted affect, avolition), several standardized assessment scales have been created.

The objective of this study was to identify a set of unidimensional instruments which allows an assessment of negative symptoms in schizophrenia and also to identify their general characteristics and the items included.

Inclusion criteria were: (a) the unidimensional assessment scales of negative symptoms of schizophrenia; (b) instruments in English (with French versions if possible); (c) all assessment instruments, the oldest and the most recent. The investigation ended in February 2013.

Twelve unidimensional instruments were identified with only one of them based on a self-administered survey (MAP-SR). The number of items included is from 6 (SDS) to 25 (SANS). The fastest instrument is the HEN (5-10min) and the longest is the SANS (30min). The MASS needs an evaluation by another person (family or care-giver). Most instruments need to be handled and take place during a semi-structured or structured psychiatric interview. The SANS allows an assessment of the most important number of negative domains (11 domains). On the other side, we have the MAP-SR (3 domains). The most frequently evaluated domains are emotional blunting, alogia, social withdrawal, anhedonia and avolition. On the other side, we have mood and thought disorders. Only SDS allows to distinguish the primary and secondary negative symptoms.

The oldest instruments (SANS, NSA-16, SDS) are more complicated to handle and to use. The SANS is the most complete instrument but there are more recent instruments which are easier to use and handle (BNSS, CAINS). Using a self-evaluation survey, MAP-SR is judicious as this type of evaluation is reliable. However, in this case, the assessment covers only a limited part of the negative symptoms.

Despite some progress in the definition, assessment and treatment of negative symptoms and despite new scales further instruments which are easy to use in clinical practice and integrating the patient's self-report are needed.