Electrophysiological correlates of CU traits show abnormal regressive maturation in adolescents with conduct problems Alexander Sumich a,b,⇑ , Sagari Sarkar b , Daniel F. Hermens c , Katerina Kelesidi b , Eric Taylor b , Katya Rubia b a Nottingham Trent University, Division of Psychology, School of Social Sciences, Nottingham NG1 4BU, UK b King’s College London, Institute of Psychiatry, London, UK c Clinical Research Unit, Brain & Mind Research Institute, University of Sydney, Australia article info Article history: Received 29 February 2012 Received in revised form 30 May 2012 Accepted 10 June 2012 Available online 21 July 2012 Keywords: Event-related potential Conduct disorder Callous-unemotional traits Maturation N200 abstract Callous/unemotional (CU) temperament traits may denote a more severe form of conduct disorder (CD) and have been associated with abnormal cortical thinning. The present study investigated the matura- tional decline in N200 amplitude, and the association between N200 amplitude and callous/unemotional traits, in adolescents with CD. Twenty adolescent males (aged 10–18 years old) with CD were age- matched to 27 clinical controls with Attention Deficit Hyperactivity Disorder (ADHD) and 30 non-clinical, typically developing controls. Participants completed a visual continuous performance task. As expected, N200 amplitude in response to background stimuli was inversely associated with age in controls (at fron- tal and temporal brain regions). Similar associations were seen in clinical controls. In contrast, the CD group showed a significant positive correlation between age and the right temporal N200 amplitude. Fur- ther, CU traits were positively correlated with N200 amplitude at midline frontal and temporal elec- trodes, even after covarying for age. These results highlight links between CU traits and abnormal neurodevelopment as indexed by N200 amplitude. This is in line with an impairment or delay in regres- sive maturational changes such as cortical thinning, as suggested by neuroimaging studies, which may underlie the persistence of certain psychopathic tendencies. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Conduct disorder (CD) is characterised by a persistent pattern of behaviour that violates either the basic rights of others or age- appropriate social norms (DSM-IV; American Psychiatric Associa- tion, 2000). Studies of causality are presently inconclusive, perhaps due to illness heterogeneity. Various genetic and environmental factors confer risk (Cappadocia, Desrocher, Pepler, & Schroeder, 2009). However, no single factor provides a satisfactory causal model (Frick, 1998). A severe child-onset subgroup of CD has been identified, with a high (25%) prevalence of callous-unemotional (CU) temperament traits: low fearfulness, absence of guilt or poor empathy (Christian, Frick, Hill, Tyler, & Frazer, 1997; Frick & Hare, 2001). This group shows more pervasive behavioural and cognitive disturbances similar to those observed in adult psychopathy (Barry et al., 2000; Liu et al., 2007; Dadds, Fraser, Frost, & Hawes, 2005), such as impaired processing of emotional stimuli (Frick & Dickens, 2006). The CD/CU clinical group appear to share unique risk factors and show a significantly greater heritability rate than non-CU groups (Frick & Dickens, 2006). Recent neuroimaging studies suggest that CU traits are under- pinned by a regionally specific absence in cortical remodelling (De Brito et al., 2009). Thus positive associations have been re- ported between CU traits and cortical thickness at frontal and tem- poral regions, which may reflect a reduction of synaptic pruning and/or poor myelination. Similarly, reduced fronto-temporal white matter (WM) has been observed in adults with psychopathy (Craig et al., 2009), whilst adolescents with CD and high CU traits show reductions right superior frontal WM concurrent to bilateral in- creases in medial frontal WM (De Brito et al., 2011). In adolescents with CD, Sarkar et al. (2012) show increased fractional anisotropy in the uncinate fasciculus, suggesting more WM connecting the ventromedial frontal cortex and amygdala. Functional imaging studies report poor activation of the right amygdala whilst viewing facial expressions of fear in boys with CD (Jones, Laurens, Herba, Barker, & Viding, 2009), which supports lesion studies in adults that implicate right fronto-temporal disturbance (including the anterior insula) in empathy (Perry et al., 2001; Gorno-Tempini et al., 2004; Kiehl, 2006; Sterzer, Stadler, Poustka, & Kleinschmidt, 2007). Event-related potentials (ERPs) are electroencephalographic (EEG) activity that is time-locked to stimulus presentation or a behavioural response. They reflect the synchronous post-synaptic potentials of large populations of cortical neurons (Coles & Rugg, 0191-8869/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.paid.2012.06.008 ⇑ Corresponding author at: Nottingham Trent University, Division of Psychology, School of Social Sciences, Nottingham NG1 4BU, UK. E-mail address: alexander.sumich@ntu.ac.uk (A. Sumich). Personality and Individual Differences 53 (2012) 862–867 Contents lists available at SciVerse ScienceDirect Personality and Individual Differences journal homepage: www.elsevier.com/locate/paid