Another concern is confounding group characteristics that will affect olfactory performance, such as those described by Brewer et al. (2003), who reported significant differences between groups for smoking and premorbid intelligence (i.e., mean IQ = 96.8 ±9.6 for those who developed schizophrenia vs. 108.5 ±9.7 in healthy controls). Of particular interest regarding the puzzling observation that the three converters showed marked threshold deficits but normal odor identification performance, a similar pattern of reduced odor thresholds but preserved odor identification as measured by the Sniffin’ Sticks was found in children with autism (Dudova et al., 2011). For the present study, there was no indication that the patient cohort differed from those of other studies (e.g., Piskulic et al., 2012). However, recruitment of healthy controls was likely different given our emphasis on ascertaining individuals having the same sociocultural background as CHR patients. Thus, one could argue that the recruitment of more closely-matched healthy controls may have accounted for the difference in SID findings between the current and prior studies. In any case, more research is warranted regarding specific aspects of olfactory processing
