Paranoid Schizophrenia (PS), yet included within the same nosological category than Non-Paranoid Schizophrenia (NPS), may in fact constitute a different disorder. In this study, the above both schizophrenia subtypes are compared with Delusional Disorder (DD). We hypothesized that, phenomenologically PS could either be a half-way category between DD and NPS or part of a phenomenological continuum of psychotic and cognitive symptoms between these three psychotic categories.
102 patients fulfilling DSM-IV-TR criteria of schizophrenia (with 56 PS and 46 with NPS) and 80 DD patients were included in this study (n=182). We compared outcome groups (DD vs. PS vs. NPS) on clinical dimensions, global functioning and sociodemographics. Clinical dimensions were extracted from the PANSS and neuropsychological scales using Principal-Component-Analysis and, subsequently, cluster analysis to assign subjects to empirically emerging clinical groups. The associations between such groups and DSM-IV-TR groups were explored using polynomial regression.
We found lineal associations demonstrating empirically that, from the psychopathological, neuropsychological and functioning perspectives, it is reasonable to consider PS as an intermediate and independent category right in between DD and NPS. Thus, the distribution of subjects assigned to three empirically emerging clinical groups (Paranoid-Affective, Paranoid-Hostile and Negative) associated, significantly and preferentially, with DSM-IV categories along the following fashion: The proportion of paranoid-hostile and, particularly, paranoid-affective subjects decreased progressively along DD, PS and NPS categories; On the contrary, the proportion of negative subjects increased lineally along those categories (Mante-Haenszel-X2= 18.02;p=0.0001). Our results question, on the bases of an empirical study, the current categorical division of paranoid psychoses.