Association Between Smaller Left Posterior Superior Temporal Gyrus Volume on Magnetic Resonance Imaging and Smaller Left Temporal P300 Amplitude in First-Episode Schizophrenia

Abstract

Background:In chronic schizophrenia, the P300 is broadly reduced and shows a localized left temporal deficit specifically associated with reduced gray matter volume of the left posterior superior temporal gyrus (STG). In first-episode patients, a similar left temporal P300 deficit is present in schizophrenia, but not in affective psychosis. The present study investigated whether the left temporal P300-left posterior STG volume association is selectively present in first-episode schizophrenia.

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

“…The substantial reduction in midline P300 amplitude in FEP-S patients relative to normal controls confirms previous findings (e.g., Salisbury et al 1998;McCarley et al 2002). However, this reduction appears to be of greater magnitude in the present study: P300 peak amplitudes in FEP-S patients were about half of that found by Salisbury et al (1998), and one third of that found by McCarley et al (2002).…”

“…However, this reduction appears to be of greater magnitude in the present study: P300 peak amplitudes in FEP-S patients were about half of that found by Salisbury et al (1998), and one third of that found by McCarley et al (2002). In addition to the differences between the experimental protocols used, a possible explanation for this discrepancy is medication.…”

“…In addition to the differences between the experimental protocols used, a possible explanation for this discrepancy is medication. In Salisbury et al (1998) andin McCarley et al (2002), patients were more medicated, with mean chlorpromazine equivalent doses of 239.6 and 262.7 mg respectively compared to 172 mg in the present study. 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.…”

“…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).…”

“…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. Thus, it is possible that the asymmetry develops, or is detectable, only after having experienced symptoms of schizophrenia for a relatively longer period of time.…”