Factor Structure of Paranoid Schizophrenia: A Prospective Study

Abstract

Paranoid schizophrenics were scored and analyzed using PANSS and principal component method on admission (T1, 480 patients), after 4 weeks (T2, 223 patients), after 8 weeks (T3, 146 patients) and after 6 months of treatment (T4, 104 patients). Seven factor models accounted for 68–74% of the variances (including models of 104 patients present at all four stages). T1 and T2 models comprised 6–7 factors and were dominated by positive and excitement symptoms. The grandiosity factor could only be identified in T1. T3 and T4 models were reduced to 5 factors and incorporated a greater expression of depressive disorders and a relatively greater expression of negative and cognitive symptoms. Negative and cognitive dimensions were the most stable elements of all the models. The concept of the depressive factor appeared to be too restrictive to describe a whole variety of the affective dimension.

Sample size requirements for the internal validation of psychiatric scales

“…The data simulation was performed using R software 2.6.2.; vectors ε j , f m and C were generated using the function rnorm and δ j using runif. (Bell et al, 1994;Fresan et al, 2005;Honey et al, 2003;Kay et al, 1990;Lancon et al, 1999;Lee et al, 2003;Lindenmayer et al, 2004;Loza et al, 2003;Lykouras et al, 2000;Salokangas et al, 2002;Villalta-Gil et al, 2006) 11 --1 8 -2 BPRS (Adachi et al, 2000;Harvey et al, 1996;Lachar et al, 2001;Ventura et al, 2000) 4 --2 1 1 -BAI (Beck, 1991;Chapman et al, 2009;Kabacoff et al, 1997;Steer et al, 1995;Steer et al, 1993) (Gabryelewicz et al, 2004;Galinowski et al, 1995;Lee et al, 2003;Parker et al, 2003;Serretti et al, 1999) 5 3 2 ----BDI (Basker et al, 2007;Bonicatto et al, 1998;Bonilla et al, 2004;Gorenstein et al, 1999;Grunebaum et al, 2005;Helm et al, 2003;Jo et al, 2007;Killgore, 1999;Munoz et al, 2007;Powell, 2003;Salamero et al, 1994;Shek, 1990;Steer et al, 1989;Uslu et al, 2008;Wang et al, 2005) …”

“…However, in each field, there are distinctive features. In psychiatry, factor loading values are usually close to 0.6, the p/M ratio can vary from three to 20 or more, depending on scales, and the number of items is often different for each factor within a scale (Dawkins et al , ; Gabryelewicz et al , ; Iwata et al , ; Loza et al , ). Another characteristic observed in psychiatric scales is the shape of the scree plot.…”

Mismatch Negativity and P3a Impairment through Different Phases of Schizophrenia and Their Association with Real-Life Functioning

“…People suffering from this disorder experience positive, disorganized, negative, depressive, extrapyramidal symptoms, cognitive impairment, as well as impairment in different areas of functioning [3,[30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48]. In particular, positive symptoms usually begin with the onset of psychosis or are present in an attenuated form in the prodromal stages; they tend to recur in conjunction with the acute phases.…”