In contrast to the main analyses of N1 sink and P2 source, some subtle group effects were observed for regional sink activities associated with P2 source. These differences originated from more variable increases in amplitude with increases in odor intensity for CHR patients at lateral frontotemporal sites, for which healthy controls showed a monotonic sink increase. While the exact meaning of these effects are not clear, these findings nevertheless underscore the greater variability in CHR patients in how these electrophysiologic measures directly reflect intensity-dependent odor detection. Thus, although these group findings provide no or little evidence of abnormal olfactory function in individuals at risk for psychosis, olfactory deficits may nonetheless prove to be a marker of risk of transition to psychosis (Brewer et al., 2003).
