Failure to differentiate between threat-related and positive emotion cues in healthy adults with childhood interpersonal or adult trauma Denise A. Chu a, b, * , Richard A. Bryant d , Justine M. Gatt a, b, c, d , Anthony W.F. Harris e, b a University of Sydney - Western Clinical School, Faculty of Medicine, NSW 2145, Australia b Brain Dynamics Centre, Westmead Institute, NSW 2145, Australia c Neuroscience Research Australia, Randwick, NSW 2031, Australia d School of Psychology, University of New South Wales, Sydney, NSW 2052, Australia e University of Sydney, Discipline of Psychiatry, NSW, Australia article info Article history: Received 28 October 2015 Received in revised form 2 March 2016 Accepted 16 March 2016 Keywords: N170 evoked evoked response potentials Childhood interpersonal trauma Adult trauma Facial emotion Non-conscious processing Healthy adults abstract Enhanced threat-related processing is associated with both elevated anxiety and childhood exposure to trauma. Given the paucity of evidence regarding the effects of childhood and adult trauma exposure on subsequent psychophysiological processes in the absence of psychopathology, we investigated the relative impacts of childhood interpersonal and non-interpersonal trauma, as well as adult trauma exposure on neural processing of threat in healthy adults. We measured peak amplitudes of the N170 face-sensitive visual ERP component response to non-conscious and conscious Angry (threat) versus Happy (non-threat, positive) and Neutral (non-threat baseline) faces at temporo-occipital sites (right-T6; left-T5) in 489 psychiatrically asymptomatic adults (aged 18e70 years, 54% women, 94% right-handed). N170 peak amplitude differences between Angry vs Happy or Neutral faces were calculated and sub- jected to hierarchical multiple regression analysis, with trauma types (childhood interpersonal, child- hood non-interpersonal and adult trauma) entered as predictors of interest. After controlling for sociodemographic and health factors, N170 peak amplitudes for non-conscious Angry vs Happy faces were inversely associated with childhood interpersonal trauma at T6 and adult trauma exposure at T5. Post-hoc repeated measures ANOVA indicated that unlike adults without trauma exposure, trauma- exposed adults failed to show significantly reduced N170 responses to Happy relative to Angry faces during non-conscious processing. This suggests that childhood interpersonal and adult trauma exposure are associated with a failure to differentiate between non-threat or positive and threat-related emotion cues. This is consistent with generalised hypervigilance seen in PTSD, and suggests trauma exposure is associated with a generalized heightened responsivity to non-conscious non-threat or positive as well as threat-related emotion cues in psychiatrically healthy adults. © 2016 Elsevier Ltd. All rights reserved. 1. Background Exposure to early life stress impacts upon the development of the neurobiological systems involved in stress and emotion regu- lation. Reported structural neural abnormalities associated with childhood trauma exposure include alterations in the corpus cal- losum (Kitayama et al., 2007) smaller hippocampal and prefrontal cortex volumes (Cohen et al., Frodl et al., 2010; Teicher et al., 2006), and larger amygdala (Lupien et al., 2011; Tottenham et al., 2010). Functional neural abnormalities in similar regions have been re- ported in association with anxiety disorders, including adult post- traumatic stress disorder (PTSD). In particular, amygdala hyperactivation and hypoactivation in medial prefrontal cortex (mPFC) structures in response to threat-related stimuli have been widely reported in these clinical groups (Etkin and Wager, 2007; Shin and Liberzon, 2010). Abnormalities in amygdala structure (Lupien et al., 2009; Tottenham et al., 2010) and reduced functional connectivity between the amygdala and mPFC structures (Marusak et al., 2015) have also been implicated in disordered stress and emotion regulation. The convergence between neurobiological abnormalities associated with childhood trauma exposure and anxiety disorders in adults, and the well-established risks of adult * Corresponding author.Brain Dynamics Centre, Westmead Institute, Hawkesbury Road, Westmead, NSW 2145, Australia. E-mail address: dchu8445@uni.sydney.edu.au (D.A. Chu). Contents lists available at ScienceDirect Journal of Psychiatric Research journal homepage: www.elsevier.com/locate/psychires http://dx.doi.org/10.1016/j.jpsychires.2016.03.006 0022-3956/© 2016 Elsevier Ltd. All rights reserved. Journal of Psychiatric Research 78 (2016) 31e41