Cognitive and Academic Functioning
Performance on WISC-V subtests was variable within and among subjects. At the individual level, mean discrepancy between participant’s highest and lowest subtest scores was 4.64 scaled score points. Fifty-nine percent (n = 36) patients had at least one subtest scaled score lower than 1 SD below the mean (i.e. a scaled score ≤ 6), with the highest proportion of low scores on the Vocabulary subtest (33%) followed by the Digit Span subtest (28%). Twenty-one percent of participants demonstrated a mean cognitive score more than 1 SDbelow age-based means. Differences in mean cognitive scores among age cohorts were present but not statistically significant (6-7 cohort M = 8.82, SD = 1.70; 11-12 cohort M = 7.78, SD = 1.65; 15-16 cohort M = 7.65, SD = 1.91; F (2, 58 = 2.45, p = .095).
The mean academic score among patients on the WJ-4 was 86.03 (SD= 14.76), with 43% of patients demonstrating mean academic scores greater than 1 SD below the mean (SS ≤ 85) compared to an expected distribution of 16% one SD below the mean. Among domains, the highest proportion of standard scores greater than 1SD below the mean (SS ≤ 85) was on the math subtest (Calculation or Applied Problems; 48%), while 52.5% (n = 32) of participants had at least one of three subtests with a standard score 1 SD below the mean. Mean academic scores were significantly lower among older age cohorts, (F(1, 57) = 3.73, p = .030), from an average standard score of 91.2 in the 6- to 7-year-old group, to 83.4 in the 11- to 12-year-old group, to 78.6 (15- to 16-year-old group).