Investigation of Heschl's gyrus and planum temporale in patients with schizophrenia and bipolar disorder: A proton magnetic resonance spectroscopy study

Background: Superior temporal cortices include brain regions dedicated to auditory processing and several lines of evidence suggest structural and functional abnormalities in both schizophrenia and bipolar disorder within this brain region. However, possible glutamatergic dysfunction within this region has not been investigated in adult patients. Methods: Thirty patients with schizophrenia (38.67 +/- 12.46 years of age), 28 euthymic patients with bipolar I disorder (35.32 +/- 9.12 years of age), and 30 age-, gender-and education-matched healthy controls were enrolled. Proton magnetic resonance spectroscopy data were acquired using a 3.0 T Siemens MAGNETOM TIM Trio MR system and single voxel Point REsolved Spectroscopy Sequence (PRESS) in order to quantify brain metabolites within the left and right Heschl's gyrus and planum temporale of superior temporal cortices. Results: There were significant abnormalities in glutamate (Glu) (F(2,78)= 8.52, p < 0.0001), N-acetyl aspartate (tNAA) (F(2,81)= 5.73, p= 0.005), creatine (tCr) (F(2,83)= 5.91, p= 0.004) and inositol (Ins) (F(2,82)= 8.49, p b 0.0001) concentrations in the left superior temporal cortex. In general, metabolite levelswere lower for bipolar disorder patients when compared to healthy participants. Moreover, patientswith bipolar disorder exhibited significantly lower tCr and Ins concentrations when compared to schizophrenia patients. In addition, we have found significant correlations between the superior temporal cortex metabolites and clinical measures. Conclusion: As the left auditory cortices are associatedwith language and speech, left hemisphere specific abnormalities may have clinical significance. Our findings are suggestive of shared glutamatergic abnormalities in schizophrenia and bipolar disorder. (C) 2014 Elsevier B. V. All rights reserved.