Abnormalities of auditory event-related potentials in schizophrenia prior to treatment

P300 asymmetry and positive symptom severity: A study in the early stage of a first episode of psychosis

“…Moreover, FEP-S patients in McCarley et al (2002) had been medicated for a longer time (158.9 days on average) before admission, while the criteria for inclusion in the present study was antipsychotic medication of no more than 30 days duration. Although general amplitude reduction has been shown to be present in non-medicated firstepisode patients (Hirayasu et al, 1998;Demiralp et al, 2002), P300 amplitude may be substantially increased by 1 Because the activity of the reference site is eliminated by the subtraction, the exact placement of the reference site has no importance for such analysis (Hagemann et al, 2001). The same analysis with ERPs obtained with an averaged reference instead of a right earlobe reference was also associated with an absence of interaction between laterality and group: [F(1,39) p values are given for one-tailed tests of significance for positive symptoms scores and GAF for which there were a priori hypotheses.…”

“…As well, older chronic patients (mean age 32.8 years) but not younger individuals (mean age 26.8) were found to have a reduced left temporal P300 (Iwanami et al 2002). As to studies of patients having suffered from a first-episode of psychosis (FEP), two did report a greater reduction of P300 over the left than the right temporal lobe (Salisbury et al, 1998;McCarley et al, 2002), whereas others, like Hirayasu et al (1998), did not describe this asymmetry. Interestingly, the mean age of the patients of the latter study was close to that of the younger patients of Iwanami et al (2002), whereas, in the two FEP studies that reported P300 asymmetry (Salisbury et al, 1998;McCarley et al, 2002), mean age was clearly greater.…”

“…The amplitude of the P300 event-related potential (ERP) is consistently reduced over midline electrodes, not only in schizophrenia patients (reviewed in Ford, 1999), their relatives (Bharath et al, 2000), subjects at high risk for schizophrenia (van der Stelt et al, 2005) and patients having suffered from a first-episode of schizophrenia (Hirayasu et al, 1998;Salisbury et al, 1998;Brown et al, 2002;McCarley et al, 2002) but also in patients with an affective psychosis (Salisbury et al, 1999;O'Donnell et al, 2004) and in several other diseases compared to normal controls (Ford, 1999).…”

Electrophysiological Deficits in Schizophrenia: Models and Mechanisms

“…Furthermore, the P3b amplitude appears to correlate inversely with the disorder's duration (Olichney et al, 1998, Mathalon et al, 2000, Martin-Loeches et al, 2001). Brown and others identified similarities in P3b amplitudes in FES and CS patients (Hirayasu et al, 1998. Similarly, unaffected first-degree relatives of patients have frequently been reported to exhibit reduced P3b amplitudes (Blackwood et al, 1991, Kidogami et al, 1991, Roxborough et al, 1993.…”

“…Thus, it is of considerable interest to determine if these abnormalities are present at onset or are exacerbated by chronicity. To address this question, few studies have investigated the P3b component in first-episode schizophrenia (FES) and consistently report a reduction in P3b amplitude as well as prolonged latencies (Hirayasu et al, 1998, Demiralp et al, 2002, Wang et al, 2003. Furthermore, the P3b amplitude appears to correlate inversely with the disorder's duration (Olichney et al, 1998, Mathalon et al, 2000, Martin-Loeches et al, 2001).…”