ORIGINAL INVESTIGATION Lateral ventricle differences between first-episode schizophrenia and first-episode psychotic bipolar disorder: A population-based morphometric MRI study PEDRO G. P. ROSA 1 , MARISTELA S. SCHAUFELBERGER 1,2 , RICARDO R. UCHIDA 1,3 , FABIO L. S. DURAN 1 , JULIA M. LAPPIN 4 , PAULO R. MENEZES 5 , MÁRCIA SCAZUFCA 5 , PHILIP K. MCGUIRE 4 , ROBIN M. MURRAY 4 & GERALDO F. BUSATTO 1 1 Department & Institute of Psychiatry, Faculty of Medicine, University of São Paulo, São Paulo, Brazil, 2 Department of Psychiatry, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil, 3 Faculty of Medical Sciences, Santa Casa de São Paulo, São Paulo, Brazil, 4 Institute of Psychiatry, King's College London, London, UK, 5 Department of Preventive Medicine, Faculty of Medicine, University of São Paulo, São Paulo, Brazil Abstract Objectives. The extent to which psychotic disorders fall into distinct diagnostic categories or can be regarded as lying on a single continuum is controversial. We compared lateral ventricle volumes between a large sample of patients with first- episode schizophrenia or bipolar disorder and a healthy control group from the same neighbourhood. Methods. Population- based MRI study with 88 first-episode psychosis (FEP) patients, grouped into those with schizophrenia/schizophreniform disorder ( N=62), bipolar disorder ( N=26) and 94 controls. Results. Right and left lateral ventricular and right temporal horn volumes were larger in FEP subjects than controls. Within the FEP sample, post-hoc tests revealed larger left lateral ventricles and larger right and left temporal horns in schizophrenia subjects relative to controls, while there was no differ- ence between patients with bipolar disorder and controls. None of the findings was attributable to effects of antipsychotics. Conclusions. This large-sample population-based MRI study showed that neuroanatomical abnormalities in subjects with schizophrenia relative to controls from the same neighbourhood are evident at the first episode of illness, but are not detectable in bipolar disorder patients. These data are consistent with a model of psychosis in which early brain insults of neurodevelopmental origin are more relevant to schizophrenia than to bipolar disorder. Key words: Psychosis, schizophrenia, bipolar affective disorder, MRI, lateral ventricles Introduction Several lines of evidence, including recent epidemio- logical (Lichtenstein et al. 2009) and molecular genetic findings (Badner and Gershon 2002), have suggested that schizophrenia should not be regarded as a nosological entity entirely distinct from other functional psychoses (Tandon et al. 2008). In par- ticular, it has been proposed that affective disorders, mainly of the bipolar type, might be placed on a diag- nostic continuum with schizophrenia (Lichtenstein et al. 2009). Detailed neurobiological investigations of this issue are of crucial importance in facilitating our understanding of the pathophysiology of the functional psychoses. Over several decades, neuroimaging studies have detected brain structural deficits in samples of schizophrenia subjects in comparisons against healthy control groups, including morphological changes in fronto-temporo-parietal cortical regions, as well as in the cingulate gyrus, thalamus, cerebellum and the ventricular system (Elkis et al. 1995; Wright et al. 2000; Steen et al. 2006; Vita et al. 2006; Ellison- Wright et al. 2008). Enlargement of the lateral ventricles has been the most replicated finding in these studies (Elkis et al. 1995; Wright et al. 2000; Vita et al. 2006), and lateral ventricles measurement, among all brain morphological indices evaluated in schizophrenia samples to date, has shown the greatest Correspondence: Professor Geraldo F. Busatto, Departamento de Psiquiatria, Faculdade de Medicina da Universidade de São Paulo, Rua Ovídio Pires Campos, s/n – CEP 05403-903, São Paulo, SP, Brasil. Tel: +55 11 30698132/30698193. E-mail: geraldo.busatto@ hcnet.usp.br. (Received 29 September 2009; accepted 24 March 2010) The World Journal of Biological Psychiatry, 2010; 11: 873–887 ISSN 1562-2975 print/ISSN 1814-1412 online © 2010 Informa Healthcare DOI: 10.3109/15622975.2010.486042