3.1. CHR Sample Characterization
HC were well matched to CHR participants on demographic variables (). The two groups did not differ significantly on age, gender or racial distribution, handedness, highest grade completed, parent education, or family income. Moreover, CHR subgroups were highly similar to HC on demographic variables, with one exception: the BIPS subgroup had higher family income.
Demographics by Group and Subgroup
3.2. Neuropsychological Performance and Profile Analysis of CHR Relative to HC
CHR and HC were highly similar on WRAT-3 Reading (). However, 38.4% (16% is expected) of CHR current WASI IQ estimates fell more than one standard deviation (SD) below the HC mean. The overall NP profile for CHR compared to HC is illustrated in . With and without olfaction included, CHR demonstrated a moderate and significant generalized deficit in NP functioning relative to HC (Cohen's d = −0.74 and −0.52, respectively). Profile analysis indicated a significant moderate to large difference in profile magnitude by group (p < 0.001 and p = 0.018, respectively). Overall, however, profiles of both groups were relatively “flat”; the overall variation of performance did not differ significantly by NP domain at the multivariate level. Differences in profile shape by group were significant at the univariate level only, and only when olfaction was included (p < .007, ηp2= 0.037). Nearly significant individual effects for both CVLT and story memory contributed to the overall verbal memory impairment; executive functioning deficits were accounted for primarily by significantly lower verbal fluency and higher WCST perseverative errors.
Neuropsychological Data by Group and Subgroup
NP Profile of Clinical High Risk (CHR) sample relative to Healthy Comparisons (HC)
3.3. NP Performance for Subgroup Developing “Severe and Psychotic” Symptoms after Baseline
Fifty-seven (78%) of 73 CHR with baseline NP data received at least two years of clinical follow-up; the other 16 CHR had a mean 7 months follow-up interval. Of the 68 without psychotic-level symptoms at baseline, 13 developed psychotic-level symptoms during the period of follow-up: one was diagnosed with schizophrenia, three with schizoaffective, three with mood, and six with brief psychosis or psychosis NOS disorders. shows their mean baseline NP profile. The effect sizes for VIQ, verbal memory and olfactory deficits in this group are large. Interestingly, whereas only one (7.7%) of the 13 had a WRAT-3 Reading score more than one SD below the HC mean, 8 (61.5%) had current IQ estimates over one SD below the HC mean. In fact, later development of psychotic level symptoms was significantly correlated with the degree to which estimated IQ was lower than WRAT-3 Reading.
NP Profiles by Development of “Severe and Psychotic” Level Symptoms
3.4. The Role of WRAT-3 Reading, WASI IQ, and Attention in Neurocognitive Profiles
The pattern of profile results remained unchanged when WRAT-3 Reading was entered as a covariate. Although statistical power was low, differences in profile shape by group at different levels of Reading were small (ηp2= 0.010 – 0.014). As shown in , the overall profile shape of CHR was strikingly similar at different levels of word reading. When analyses were repeated using a median split of estimated current (WASI) IQ, differences in the profile shape by group at different levels of global impairment were again small (ηp2= 0.006 – 0.009) and nonsignificant. As shown in , CHR and HC profiles were very similar at both high and low levels of IQ except on olfactory functioning. That is, the overall pattern of NP strengths and weaknesses showed similar variation by level of IQ for both CHR and HC. Finally, basic results of profile analyses did not differ when attention was entered as a covariate.
Group Profiles by Median Split of WRAT-3 Reading Score
Group Profiles by Median IQ Split