Abstract
Background
The early psychosis is classically viewed as a critical period. Schizophrenia subtypes which had been used to describe heterogeneity of the disease were discarded with the release of DSM-5 because of the lack of their clinical significance. DSM-5 has proposed the use of the Clinician-Rated Dimension of Psychosis Symptom Severity (CRDPSS) for evaluating the various symptoms of schizophrenia. The 8-domain CRDPSS was developed from the perspective of deconstructing the psychopathology of schizophrenia and would be expected to provide baseline data for further advances in psychiatric nosology. To our knowledge, despite these discussions, the dimensional structure of the CRDPSS has hardly been studied in the patients with early psychosis. The purpose of this study is to investigate the structure categorizing the items of dimensional assessment through factor analysis in patients with early psychosis.
Methods
The subjects were 497 patients with early psychosis who were enrolled in the Korean Early Psychosis Cohort Study. They were between ≥18 years and ≤45 years of age who fulfill the criteria of DSM-5 for schizophrenia spectrum and other psychotic disorders. In KEPS, early psychosis was defined the patients whose duration of treatment were within 2 years. The proportion of males was 41.9% and their mean age and age at onset were 28.7(SD=8.9) and 26.8(SD=9.1) years, respectively. An exploratory factor analysis(EFA) was conducted on the 8 items of dimensional assessment of psychosis in DSM-5 with principle components extracted by the varimax method.
Results
An exploratory factor analysis(EFA) was conducted on the items of dimensional assessment of psychosis in DSM-5 with principle components extracted by the varimax method. Two factors were identified which were labeled as ‘psychotic’ and ‘deficit’ domain. The first factor included delusions (loading=0.834, communality=0.697), hallucinations(loading=0.800, communality=0.640), disorganization(loading=0.654, communality=0.642), and abnormal psychomotor behavior(loading=0.677, communality=0.549). The second factor included negative symptoms(loading=0.833, communality=0.703) and impaired cognition(loading=0.827, communality=0.697). Depression and mania were excluded in factor analysis due to statistical incompatibility such as lack of communality less than 0.4. Bartlett’s test for sphericity was significant (χ2 =817.996, p<0.001), and the total variance of the factor solution was 65.452%.
Discussion
Two factors were identified which were labeled as ‘psychotic’ and ‘deficit’ domain. The first factor included delusions, hallucinations, disorganization and abnormal psychomotor behavior. The second factor included negative symptoms and impaired cognition. To our knowledge, this study is the first attempt to analyze the early psychosis patients using the dimensional assessment of psychosis in DSM-5, and it would be meaningful to follow up the course with the cohort.
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