Treatment resistant schizophrenia (TRS) is a severe type of schizophrenia characterized by persistent psychotic symptoms, poor response to antipsychotic medications, and functional deterioration. Historically, negative symptoms have been considered as an important feature of schizophrenia with a poor prognosis, including TRS. However, later generations of definitions of TRS had undermined the role of negative symptoms. The most recent treatment response and resistance in psychosis (TRRIP) consensus guideline incorporated negative symptoms as a feature of TRS, but empirical research on the nature and patterns of negative symptoms in TRS patients remained limited.

To address this issue, Dr. Raymond Chan from the Institute of Psychology of the Chinese Academy of Sciences, together with his collaborators at the University of Hong Kong and Castle Peak Hospital Hong Kong, have designed a cross-sectional study to measure negative symptoms using second-generation scales in patients with TRS.

They recruited 206 patients with TRS, and empirically categorized them based on Clinical Assessment Interview of Negative symptoms (CAINS)-negative symptoms, self-report experiential pleasure and emotion expressivity. The functioning of different TRS clusters were compared.

Results showed three resultant clusters. Two clusters had more severe CAINS-negative symptoms, and another cluster had low CAINS-negative symptoms. Of the two negative symptom TRS clusters, one showed low experiential pleasure and another showed low emotional expressivity.

When the three clusters were validated using the Brief Negative Symptom Scale (BNSS) and Social and Occupational Functional Assessment (SOFAS), the researchers found that the negative symptoms TRS cluster with low experiential pleasure exhibited the lowest functioning in terms of SOFAS.

These findings supported the important role of negative symptoms in TRS patients in determining their social functioning. Moreover, the results supported the heterogeneity of negative symptoms in TRS, paving the way for the applications of the CAINS and BNSS in the definition of TRS according to the TRRIP guideline.

This study was published online in Schizophrenia Research on 13 July and it was supported by the Philip K.H. Wong Foundation.