28.4 Relationship Between Sluggish Cognitive Tempo, IQ and Academic Achievement Test Scores, and Academic Impairment in Autism Spectrum Disorder, ADHD, and Elementary School Samples

Abstract

Sluggish cognitive tempo (SCT) symptoms include spacey, staring, daydreaming, in own world, slow thinking and responding, sluggish, underactive, and drowsy. SCT has strong convergent and divergent validity. This study investigates correlations between SCT and IQ and academic functioning and determines if SCT is a significant independent predictor of academic functioning. The sample comprised 1443 children (6-16 years old); among those, there were 218 with autism spectrum disorder (ASD), 489 with ADHD-Combined, 187 with ADHD-Inattentive, and 549 elementary school students. All children had an IQ ≥80. Children were rated by their mothers on the Pediatric Behavior Scale (PBS), and children with ASD/ADHD were also rated by teachers. The PBS assesses SCT, ADHD, ODD and conduct disorders, anxiety, depression, somatic complaints, and cognitive and learning problems. Children in the ASD/ADHD sample were administered the Wechsler Intelligence Scale for Children (WISC) and Wechsler Individual Achievement Test (WIAT). Children in the elementary school sample were administered the Wechsler Abbreviated Scale of Intelligence, Digit Span, Coding, and Wide Range Achievement Test. Correlations between SCT and IQ (verbal, nonverbal, working memory, and processing speed) and reading, math, and written expression achievement scores were all negative, with a pattern of decreasing scores with increasing SCT. Correlations were small (r = –0.01 to –0.15) and nonsignificant, except for processing speed and timed math, but the explained variance for these was only 2%. In regression analysis, SCT was not a significant predictor of achievement scores or academic impairment ratings. The strongest predictors were IQ for achievement scores and mother and teacher ratings of cognitive impairment for mother and teacher academic impairment ratings, respectively (explained variance = 23%-63%; p < 0.0001). Mother and teacher inattention ratings predicted mother and teacher academic impairment ratings, respectively. Ratings of SCT, impulsivity, hyperactivity, anxiety, depression, and ODD and conduct disorder were nonsignificant. SCT was not an independent predictor of achievement scores or mother and teacher academic impairment ratings when other variables were controlled. Inattention is more strongly related to academic functioning than is SCT.