There is ample evidence of neurophysiologic abnormalities in schizophrenia and unaffected relatives for processing auditory or visual stimuli, although prominent ERP reductions, such as the decrease in P3 amplitude, are not specific to schizophrenia (e.g., Ford, 1999; Javitt et al., 2008; Winterer et al., 2003). Of relevance for high risk studies, P3 amplitude reduction has elements of being both a state and trait marker of schizophrenia (e.g., Mathalon et al., 2000). In CHR patients, several studies have reported abnormalities of auditory P3 amplitude (e.g., Frommann et al., 2008; van Tricht et al., 2010; van der Stelt et al., 2005) and duration mismatch negativity (e.g., Atkinson et al., 2012; Bodatsch et al., 2011; Shaikh et al., 2012), as well as for visual ERPs during recognition of facial affect (e.g., Wölwer et al., 2012), which has been linked to odor identification in schizophrenia (Kohler et al., 2007).
