Table 4.
Intellectual (IQ) performance and neurocognitive Z scores by group at baseline and post-psychosis onset/retest
| Variable | Visit | CNTL | Meds-free CHR+NT | Meds-matched CHR+NT | CHR+T |
p values
|
||
|---|---|---|---|---|---|---|---|---|
| Group | Visit | Group × visit | ||||||
| IQa | Time 1 | 111.80 (2.89) | 107.20 (3.89) | 104.53 (4.22) | 92.60 (3.48) | 0.002 | 0.82 | 0.97 |
| Time 2 | 111.50 (2.34) | 107.59 (4.84) | 106.55 (5.06) | 92.13 (3.52) | ||||
| Global neurocogitive composite | Time 1 | 0.23 (0.13) | −0.06 (0.13) | −0.29 (0.23) | −1.44 (0.32) | <0.001 | 0.11 | 0.85 |
| Time 2 | 0.28 (0.14) | 0.10 (0.15) | −0.14 (0.25) | −1.25 (0.33) | ||||
| Verbal memory | Time 1 | 0.37 (0.23) | −0.13 (0.17) | −0.30 (0.27) | −1.82 (0.33) | 0.001 | 0.34 | 0.15 |
| Time 2 | −0.16 (0.38) | −0.13 (0.38) | 0.40 (0.31) | −1.26 (0.31) | ||||
| Processing speed | Time 1 | 0.25 (0.26) | −0.51 (0.27) | −0.64 (0.34) | −1.98 (0.37) | <0.001 | 0.03 | 0.17 |
| Time 2 | 0.53 (0.33) | 0.41 (0.38) | −0.52 (0.52) | −1.88 (0.39) | ||||
| Sustained attention | Time 1 | 0.23 (0.24) | −0.25 (0.28) | −0.30 (0.29) | −1.60 (0.31) | 0.001 | 0.01 | 0.73 |
| Time 2 | 0.67 (0.22) | 0.14 (0.22) | −0.2 (0.26) | −1.24 (0.38) | ||||
| Executive function | Time 1 | 0.25 (0.25) | −0.29 (0.23) | −0.26 (0.32) | −1.44 (0.47) | 0.05 | 0.85 | 0.29 |
| Time 2 | 0.55 (0.47) | −0.51 (0.37) | −0.75 (0.72) | −0.87 (0.45) | ||||
| Working memory | Time 1 | 0.06 (0.25) | 0.22 (0.26) | 0.17 (0.32) | −1.23 (0.37) | 0.002 | 0.35 | 0.80 |
| Time 2 | −0.20 (0.29) | 0.18 (0.25) | 0.21 (0.32) | −1.50 (0.34) | ||||
| Language | Time 1 | 0.66 (0.22) | 0.21 (0.26) | 0.00 (0.31) | −0.92 (0.35) | 0.02 | 0.82 | 0.74 |
| Time 2 | 0.55 (0.26) | 0.10 (0.14) | 0.33 (0.28) | −0.88 (0.48) | ||||
CNTL, Healthy comparison subjects; CHR+NT, CHR+ subjects who did not transition to psychosis; CHR+T, CHR+ subjects who did transition to psychosis.
Scores are presented as z scores (standard error of the mean) and are estimated marginal means derived from the linear mixed models. A main effect of time along with a group × time interaction would support evidence of a decline specific to the converters. Failing to find worsening in neurocognitive performance for the converters after the onset of psychosis, along with a significant difference between the four groups would suggest a pre-existing cognitive impairment for those who go on to develop a full-blown psychotic disorder.
Estimated full-scale IQ scores were derived from the vocabulary and block design subscales of the Wechsler Intelligence Scale for Children – Third Edition for subjects aged <16 years and from the Wechsler Adult Intelligence Scale – Revised for subjects aged ≥16 years.