Inferior Parietal Lobule Volume and Schneiderian First-Rank Symptoms in Antipsychotic-Naïve Schizophrenia: A 3-Tesla MRI Study

BACKGROUND: As per Frith's neuro-cognitive model, inferior parietal lobule (IPL) is implicated in the pathogenesis of Schneiderian first-rank symptoms (FRS) in schizophrenia. The specific role of IPL structural abnormalities in the pathogenesis of FRS is yet to be ascertained. MATERIALS AND METHODS: Using 3-tesla MRI scanner, this first-time study examined antipsychotic-naïve schizophrenia patients ( n = 28) (patients with FRS [FRS +]: N = 14, M: F = 7:7; and patients without FRS [FRS-]: N = 14, M: F = 7:7) in comparison with sex-, handedness-, education- and socioeconomic status-matched healthy controls (n = 14, M: F = 7:7). The volume of IPL was measured using a three-dimensional, interactive, semi-automated analysis, with good inter-rater reliability. RESULTS: FRS + patients showed significant volume deficit in right IPL in comparison with healthy controls (F = 4.0; P=.028) after controlling for the potential confounding effects of age, sex and intracranial volume. CONCLUSIONS: Right IPL volume deficit in FRS+patients adds further support to the Frith's model of FRS in schizophrenia.