PATTERNS OF POSITIVE AND NEGATIVE SYMPTOMS IN FIRST EPISODE SCHIZOPHRENIA

Background. The aim is to examine, in first episodes of schizophrenia, the appropriateness of the simple two-dimensional model of schizophre nia ('negative' and 'positive' dimensions) and more complex variants. Method. All patients with a first episode of schizophrenia who, over a two-year period, made contact with any of the public mental health se rvices of the autonomous region of Cantabria in northern Spain were in vestigated. The psychiatric evaluation included, among other instrumen ts, the Present State Examination (PSE-9), and the scales for the asse ssment of the positive' and negative' symptoms of schizophrenia (SAPS and SANS respectively). The dimensionality of the SAPS/SANS item score s and sub-scales was examined through the use of principal component a nalysis. Results. The principal component solution that best fits the data obtained with the initial SANS/SAPS sub-scales reflects the exist ence of three different ('negative', 'positive', 'disorganisation') fa ctors. The strategy adopted of repeating the analysis after extracting the principal components of the original sub-scales, revealed that al though the nature and item composition of the initial 'negative' and ' disorganisation' factors were in general confirmed, the 'positive' dim ension presented a more complex structure with at least two 'positive' ('Non-Paranoid' and 'Paranoid') independent factors. Conclusion. The psychopathological structure of the early stages of schizophrenia, as evaluated by the SANS/SAPS, is characterised by the presence of four d imensions: two 'positive' one 'negative' and one 'disorganisation'.