Clin Psychopharmacol Neurosci.  2021 Aug;19(3):507-513. 10.9758/cpn.2021.19.3.507.

Pars Triangularis Volume Asymmetry and Schneiderian First Rank Symptoms in Antipsychotic-naïve Schizophrenia

• Shivakumar V
• Sreeraj VS
• Kalmady SV
• Gangadhar BN
• Venkatasubramanian G

• KMID: 2519558
• DOI: http://doi.org/10.9758/cpn.2021.19.3.507

Abstract

Objective
Schizophrenia is a disorder of language and self, with first-rank symptoms (FRS) as one of the predominant features in a subset of patients. Abnormal language lateralization is hypothesized to underlie the neurobiology of FRS in schizophrenia. The role of Broca’s area with its right-hemispheric counterpart, consisting of pars triangularis (PTr) and pars opercularis (POp) of the inferior frontal gyrus in FRS is undetermined. We compared the volumes and asymmetries of PTr & POp in anti-psychotic-naive schizophrenia patients with FRS (FRS[＋]) with those without FRS (FRS[−]) and healthy-controls (HC) using three dimensional, interactive, semi-automated volumetric morphometry.
Methods
Antipsychotic naïve FRS(＋) (n = 27), FRS(−) (n = 24) and HC (n = 51) were carefully assessed with structured and semi-structured clinical tools. T1-weighted images were acquired in a 3T scanner. Volumes of regions of interest were measured independently for both sides using slicer-3D software, and asymmetry indices were calculated.
Results
FRS(＋) but not FRS(−) had a significant volume deficit in right PTr after controlling for the potential confounding effects of age, sex, and intracranial volume (p = 0.029). There was a significant leftward asymmetry of PTr in patients with FRS (i.e., leftward asymmetry in patients) (p = 0.026). No significant volume/asymmetry abnormalities were observed in POp.
Conclusion
Study findings suggest reduced right PTr volume with leftward asymmetry to be associated with FRS in schizophrenia. This is consistent with the loss of Yakovlevian torque in schizophrenia. Role of PTr in the neurobiology of schizophrenia as a disorder of self, speech, and social cognition needs further systematic evaluation in future research.

Keyword

Schizophrenia; Broca area; Language; Schneiderian first-rank symptoms