Increased spontaneous gamma power and synchrony in schizophrenia patients having higher minor physical anomalies Sai Krishna Tikka a,n , Shamsul Haque Nizamie a , Basudeb Das a , Mohammad Zia Ul Haq Katshu b , Nishant Goyal a a Department of Psychiatry, Central Institute of Psychiatry, Kanke, Ranchi 834006, Jharkhand, India b School of Psychology, Bangor University, Bangor, Wales LL57 2AS, United Kingdom article info Article history: Received 3 May 2012 Received in revised form 29 July 2012 Accepted 6 September 2012 Keywords: Schizophrenia Minor physical anomalies Gamma oscillations Neurodevelopment Electroencephalogram (EEG) abstract The higher frequency of minor physical anomalies (MPAs) in schizophrenia provides morphological evidence for the neurodevelopmental theory. Abnormal gamma oscillations ( 430 Hz) seen in the electroencephalogram (EEG) in schizophrenia have been hypothesized to result from developmental insults. This study investigated spontaneous gamma oscillations in schizophrenia patients having higher and lower number of MPAs. Forty drug naı¨ve/free schizophrenia patients and 20 matched healthy controls were assessed for MPAs on the Extended Waldrop Scale (EWS). All participants underwent an awake, resting 192-channel EEG recording. Spontaneous gamma spectral power and coherence were estimated in the low- (30–50 Hz) and high-gamma (51–70 and 71–100 Hz) bands. Significantly higher power was observed in high-MPA than healthy control group in low-gamma band over right frontal, parietal and temporal regions. Spectral power in the high-gamma band (71–100 Hz) was also significantly higher in the high-MPA schizophrenia subgroup than in the healthy control group over left frontal, parietal and temporal regions. Additionally, regional intra-hemispheric and inter- hemispheric coherence in the low-gamma band was significantly higher in the high-MPA schizophrenia subgroup than on the healthy control group. This study is the first to provide evidence of increased spontaneous gamma power and synchrony in schizophrenia patients having higher MPAs, supporting the idea that it may represent a distinct subgroup of schizophrenia with a neurodevelopmental basis. & 2012 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Schizophrenia is conceptualized as a neurodevelopmental disorder with increasing evidence from genetics, environmental factors, and brain pathology research to support this view (Fatemi and Folsom, 2009). The developmental insults may start as early as the first trimester in-utero leading to abnormal development of neural net- works that manifest as schizophrenia symptoms later in life (Rapoport et al., 2005). Morphological evidence of the developmental insults has been consistently documented in schizophrenia patients in the form of minor physical anomalies (MPAs). MPAs are fixed physical defects or deviations in appearance from essential physical characteristics that are of little functional significance (Evans et al., 1973). In a meta-analysis of 13 studies, Weinberg et al. (2007) found significantly more overall and regional MPAs, without any regional specificity, in schizophrenia patients compared to controls. However, MPAs in the craniofacial region may be more specifically linked to neurodevelopmental insults considering their concurrent in-utero development with neural structural changes associated with schizo- phrenia. Consistent with this, a higher discriminant value of MPAs in the craniofacial region in classifying schizophrenia patients and controls has been found (Lane et al., 1997; Akabaliev et al., 2001; Compton et al., 2009; 2011). MPAs have been associated with cognitive (Guy et al., 1983; Green et al., 1989; Alexander et al., 1994; McGrath et al., 1995; Ismail et al., 2000; Mittal and Walker, 2011), neurological (Waldrop et al., 1968; Marcus et al., 1985; Nizamie et al., 1989; Lawrie et al., 2001; Gourion et al., 2003, 2004; Compton et al., 2007; John et al., 2008), neuroanatomical (Alexander et al., 1994; Buckley et al., 1994; McGrath et al., 1995; O’Callaghan et al., 1995; Dean et al., 2006) and biochemical (Mittal and Walker, 2011) abnormalities in schizophrenia patients, although with inconsistent results. Curiously, however, there has been no attempt to study the association between MPAs and electroence- phalographic (EEG) abnormalities in schizophrenia. Neural oscillations in the gamma range ( 430 Hz) play an important role in the development and maturation of cognitive functions like sensory processing, attention and working memory (Traub et al., 1996; Tallon-Baudry and Bertrand, 1999; Jensen et al., 2007; Uhlhaas et al., 2011). The maturation of gamma oscillations in terms of amplitude and synchrony continues Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/psychres Psychiatry Research 0165-1781/$ - see front matter & 2012 Elsevier Ireland Ltd. All rights reserved. http://dx.doi.org/10.1016/j.psychres.2012.09.006 n Corresponding author. Tel.: þ91 8298041330 (mob); fax: þ96512233668. E-mail address: cricsai@gmail.com (S.K. Tikka). Psychiatry Research 207 (2013) 164–172