Functional and structural brain asymmetries in patients with schizophrenia and bipolar disorders Céline Royer a , Nicolas Delcroix b , Elise Leroux a,c , Mathieu Alary a , Annick Razafimandimby a,d , Perrine Brazo a,c,e , Pascal Delamillieure a,c,e , Sonia Dollfus a,c,e, ⁎ a CNRS, UMR 6301 ISTCT, ISTS Team, GIP CYCERON, Bd Henri Becquerel, BP5229, F-14074 Cedex Caen, France b CNRS, UMS 3408, GIP CYCERON, Bd Henri Becquerel, BP5229, F-14074 Cedex Caen, France c CHU de Caen, Service de Psychiatrie, Centre Esquirol, Caen, F-14000, France d Université de Caen Basse-Normandie, IBFA, Caen, F-14000, France e Université de Caen Basse-Normandie, UFR de médecine (Medical School), Caen, F-14000, France abstract article info Article history: Received 14 June 2014 Received in revised form 15 November 2014 Accepted 15 November 2014 Available online xxxx Keywords: Schizophrenia Bipolar disorders Language Functional hemispheric lateralization Gray matter volume asymmetry MRI Objectives: This study aimed to compare the functional and gray matter asymmetries in patients with schizophrenia (SZ), patients with bipolar disorders (BD), and healthy controls (HCs) to test whether decreased leftward functional hemispheric lateralization and gray matter volume asymmetry could mark the boundary between schizophrenia and bipolar disorder. Methods: A total of 31 right-handed SZ and 20 right-handed BD underwent a session of functional MRI with a speech listening paradigm. Participants were matched with HCs for gender, age, and education. Functional laterality indices (FLI) and gray matter volume asymmetry indices (GVAI) were computed from the individual functional language network. Correlations between the FLI and GVAI indices were also examined. Results: SZ exhibited significantly decreased leftward functional hemispheric lateralization whereas BD did not. The GVAIs did not differ significantly between SZ and HCs or between BD and HCs. There were positive correlations between GVAIs and FLIs in all groups. Conclusions: Loss of laterality for language comprehension with retention of gray matter volume asymmetry indicates that gray matter loss alone will not account for the pathophysiology of schizophrenia. Impaired leftward functional hemispheric lateralization for language but not gray matter volume asymmetry can be considered a biomarker of SZ. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Specificity of cerebral markers in patients with schizophrenia (SZ) or bipolar disorders (BD) must be considered in light of the debate on the nosological delimitation of the two disorders (Lake and Hurwitz, 2007). Few functional magnetic resonance imaging studies investigating lan- guage networks have sought to identify cerebral biomarkers to discrim- inate these patient groups (McIntosh et al., 2008; Maïza et al., 2010; Whalley et al., 2012). Nevertheless, some authors have reported decreased leftward functional lateralization for language in SZ patients (Sommer et al., 2003; Dollfus et al., 2005; van Veelen et al., 2011; Sheng et al., 2013), and one previous study suggested that change in functional hemispheric lateralization for language could be a biomarker of SZ (Alary et al., 2013b). However, gray matter volume changes in lan- guage structures in SZ and BD patients have been little investigated (Ratnanather et al., 2013). Therefore, the present study compared functional and gray matter asymmetries among SZ patients, BD patients, and healthy controls (HCs). We hypothesized that decreased leftward functional hemispheric lateralization and gray matter volume asymme- try in a language network would be specifically observed in SZ patients but not in BD patients. 2. Materials and methods 2.1. Participants A total of 31 SZ and 20 BD (Diagnostic and Statistical Manual of Mental Disorder 4th Edition; DSM-IV) were included after giving in- formed written consent and with the agreement of the local ethics Schizophrenia Research xxx (2014) xxx–xxx Abbreviations: AHRS, Auditory Hallucinations Rating Scale; ARS, Association de Recherche pour la Schizophrénie; BD, bipolar disorders; CS, comprehension score; DSM- IV, Diagnostic and Statistical Manual of Mental Disorder 4th edition; FLI, functional laterality index; FLI int , intermediate functional laterality index; FWE, family-wise error; GVAI, gray matter volume asymmetry index; GVAI int , intermediate gray matter volume asymmetry index; HC, healthy control; HCL-20, hypomania checklist; HRSD, Hamilton Rating Scale for Depression; MNI, Montreal Neurological Institute; MRI, magnetic resonance imaging; nCS, normalized comprehension score; PANSS, Positive and Negative Syndrome Scale; SPM, Statistical Parametric Mapping; SZ, schizophrenia ⁎ Corresponding author at: Centre Esquirol, CHU Caen, Caen 14000, France. Fax: +33 231068749. E-mail address: dollfus-s@chu-caen.fr (S. Dollfus). SCHRES-06153; No of Pages 5 http://dx.doi.org/10.1016/j.schres.2014.11.014 0920-9964/© 2014 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Schizophrenia Research journal homepage: www.elsevier.com/locate/schres Please cite this article as: Royer, C., et al., Functional and structural brain asymmetries in patients with schizophrenia and bipolar disorders, Schizophr. Res. (2014), http://dx.doi.org/10.1016/j.schres.2014.11.014