Everything you need to know the SNS scale

The SNS scaleSelf-Assessment Scale for Negative Symptoms – provides a unique and effective approach for patients wishing to understand and assess their negative symptoms in psychiatry.

Why are symptoms termed "negative"?

Symptoms are termed “negative” because they represent a deficit in functions, as opposed to “positive” symptoms which indicate an excess of functions such as hallucinations or delusions.

The 5 dimensions of negative symptoms in the SNS scale

These symptoms are characterized according to five main dimensions:

  1. Social Withdrawal: A noticeable reduction in social activities.
  2. Anhedonia: Difficulty in feeling pleasure.
  3. Alogia: Reduced speech output.
  4. Affective Blunting: Inability to express emotions.
  5. Avolition: Lack of motivation and difficulty initiating and following through with an action plan.

Their precise identification is crucial as they largely contribute to a functional deficit in the patient.

Benefits of Self-assessment

Self-assessment allows for a deeper awareness of symptoms and actively engages the patient in their healing process. While other tools exist to evaluate negative symptoms, the SNS scale is the only one allowing patients to self-assess these five essential dimensions.

Specific Features of the SNS scale

The SNS scale, stemming from an in-depth study primarily based on testimonials from French patients, is a concise and easy-to-understand scale. Designed in France, it is structured into 20 short statements, each depicting a specific negative symptom. The five dimensions mentioned are represented by four distinct statements each. When using it, the patient selects one of the three proposed responses for each statement. These choices generate a total score, ranging from 0 to 40, and five sub-scores, each ranging from 0 to 8, to assess the severity of the symptoms.

The SNS (Self-evaluation of negative symptoms) is a scale allowing the patient to assess themselves their negative symptoms.

 The symptoms are said to be “negative” because they refer to a deficit of functions, as opposed to the so-called “positive” symptoms (such as hallucinations and delirium) which refer to an excess of functions.

These negative symptoms are described along 5 dimensions: social withdrawal (reduction in social activities), anhedonia (reduction in the ability to experience pleasure), alogia (reduction in the amount of speech), blunted affect (reduced ability to express emotions), avolition (reduced motivation and difficulty maintaining a plan of action). These negative symptoms are recognized as being strongly responsible for a functional deficit. Consequently, their identification by the patient him/herself allows to set up personalized support measures.

Up to now, there are several scales based on observer rating that measure the intensity of negative symptoms in patients with schizophrenia, but the self-assessment of negative symptoms (SNS) is the only self-evaluation that allows the patient to self-assess their negative symptomatology taking into account its five dimensions.

Conceived mostly from French patients’ verbatim, this self-assessment is concise and easily understandable.

The SNS, whose original version is in French, consists of 20 short sentences, each describing a negative symptom. Each of the five dimensions of negative symptomatology (alogia, social withdrawal, anhedonia, diminished emotional range and avolition) is described with four sentences. For each sentence, the patient ticks one of three answers, to which a score is assigned (2 for “Strongly agree”, 1 for “Somewhat agree and 0 for “Strongly disagree”). Thus, a total score (from 0 to 40) and five subscores (from 0 to 8) are generated based on the severity of the negative symptoms and their 5 dimensions.

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