Schizophrenia patients may be classified into three distinct subgroups, based on levels of social cognition and negative symptoms, that are associated with differences in community integration and quality of life, US study findings suggest.
The researchers, led by Morris Bell (VA Connecticut Healthcare System, West Haven, USA), report in Schizophrenia Bulletin: "We believe our results support separate domains and the need for separate interventions (pharmacologic or psychosocial)…It is improbable that they all can benefit equally from the same 'residual phase' treatment."
The team administered a psychosocial interview, the Quality of Life Scale, and a series of social cognition tests, including the MCCB Social Cognition Index (MSCEIT), as well as the Scale for the Assessment of Negative Symptoms (SANS) and the Positive and Negative Syndrome Scale (PANSS), to 77 outpatients diagnosed with schizophrenia or schizoaffective disorder.
K-means cluster analysis produced three easily identifiable groupings: a high negative symptom group (HN) and two low negative symptom groups with high social cognition (HSC) and low social cognition (LSC).
Overall, HSC patients scored consistently better on all quality-of-life scales, and had higher rates of marriage than other patients. In comparison, LSC patients had twice the number of arrests than HN or HSC patients, at 52.0%, 29.2%, and 18.5%, respectively.
Further analysis showed that 87.5% of HN, 85.2% of HSC, and 80.8% of LSC patients could be accurately classified using just the MSCEIT and PANSS negative component, with an overall classification accuracy of 84.4%. Defining a rule of thumb classification with a PANSS negative factor cutoff of >19 and an MSCEIT cutoff of >37 also gave a concordance with K-means cluster analysis of 84.4%.
When the rule of thumb was applied to a sample of 63 outpatients, LSC patients had significantly more arrests than HN and HSC patients, at 85.7% versus 20% and 22.2%, respectively, and had a higher incidence of lifetime substance abuse, at 100% versus 80% and 62.5%, respectively. These findings were repeated when the rule of thumb was applied to the original cohort.
The authors conclude: "Our cluster analysis suggests that subgroups may exist with differences in underlying pathology manifesting in differences along the negative and social cognition dimensions. Distinguishing rather than lumping these subgroups may shed light on different etiological processes as well as point to more specific treatments."
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