Negative Symptoms of Schizophrenia and Their Assessment
Schizophrenia is a serious psychiatric disorder with a prevalence of up to 1%. It can manifest with both negative and positive symptoms. We briefly summarize the clinical assessment and rating scales of negative symptoms in the following text.
Assessment of Negative Symptoms of Schizophrenia
When assessing the negative symptoms of schizophrenia, it is ideal to combine information obtained during an interview not only with the patient but also with members of their family. Information obtained from healthcare professionals can also be valuable. We first let the patient talk spontaneously about what has happened over the past week or the previous day. However, spontaneous reporting is often sparse, and it is necessary to conduct a structured interview. We ask about studies or employment and daily activities, such as shopping, household care, personal hygiene, time spent with family and friends, or intimate life.
During the interview, we focus on the so-called 5As: affective flattening (emotional flattening), alogia (poverty of speech and thought), asociality (social withdrawal), anhedonia (loss of pleasure), avolition (hypobulia, lack of motivation).
The examination takes about 20–30 minutes. In addition to the clinical examination, some rating scales can be used.
Rating Scales
The Brief Psychiatric Rating Scale (BPRS) focuses on 3 negative symptoms: emotional flattening, emotional withdrawal, and motor retardation, which is debatable. These are rated on a scale from 0 (absent) to 6 (extremely present).
The PANSS (Positive and Negative Syndrome Scale) rates a total of 7 items on a scale from 1 (absent) to 7 (extremely present). Recent factor analysis removed items “difficulty in abstract thinking” (N5) and “stereotyped thinking” (N7). Marder’s negative factors included items “motor retardation” (G7) and “active social avoidance” (G16).
The first widely adopted standalone scale for assessing negative symptoms was the SANS (Scale for the Assessment of Negative Symptoms), which consists of 5 domains.
In the late 1980s, the NSA (Negative Symptom Assessment) scale was developed. It was shortened from the original 25 items to 16, each scoring 0–6. Administration takes 15–30 minutes and assesses communication, affect and emotions, sociality, motivation, and retardation. There is also a short 4-item version that includes the following items: reduced speech production, reduced range of emotions, reduced social activities, and reduced interest.
New scales have responded to the inaccuracies of older rating scales. The Brief Negative Symptom Scale (BNSS) consists of 13 items using a 7-point scale from 0 (normal) to 6 (extremely severe). It is based on a semi-structured interview, where, in addition to patient behavior, their subjective experiences are also assessed. The scale covers a total of 6 subscales (anhedonia, lack of excitement from negative events, social withdrawal, avolition, flattened affect, and poverty of speech).
The second new-generation tool for assessing negative symptoms is the CAINS (Clinical Assessment Interview for Negative Symptoms). It consists of 13 items, 4 of which cover expression and 9 concern motivation and pleasure in areas of family and friends, employment or studies, and leisure activities. All items are rated on a scale of 0–4 based on severity. Both behavior and information regarding the patient's environment and psychological experiences are taken into account during assessment. It is one of the few psychiatric rating scales where validity and reliability can be verified.
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Source: Masopust J., Mohr P., Kopeček M. Cariprazine - an antipsychotic (not only) for the treatment of negative symptoms of schizophrenia. Galén, Prague, 2021: 87–96.
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