Relationship between sluggish cognitive tempo, IQ and academic achievement test scores, and academic impairment in autism, ADHD, and elementary school samples

Sluggish cognitive tempo (SCT) is of renewed interest. The relationship between SCT, IQ and achievement scores, and academic impairment ratings was investigated in 218 students with autism and 676 with ADHD (6–16 years) and 549 elementary school students (IQ ≥ 80). Mothers rated their children on the Pediatric Behavior Scale. Children in the autism/ADHD sample were also rated by teachers. Correlations between SCT and IQ and achievement scores (Verbal Comprehension, Perceptual Reasoning, Working Memory, Processing Speed, reading, math, and written expression) were all negative and were nonsignificant in the total autism/ADHD and elementary school samples, except for small correlations with Processing Speed and a timed math test. In contrast, mother and teacher SCT ratings were significantly related to mother and teacher academic and cognitive impairment ratings. SCT was not a significant predictor of achievement scores or academic impairment ratings in regression analysis. The strongest predictor of achievement test scores was IQ, and the strongest predictors of academic impairment were mother and teacher cognitive impairment ratings. Teacher inattention ratings predicted teacher academic impairment ratings in autism/ADHD and mother inattention ratings predicted mother academic impairment ratings in elementary school children. Therefore, inattention was more predictive of academic functioning than was SCT. Research shows a weak link between SCT and processing speed (contrary to what is implied by the term sluggish cognitive tempo), and other neuropsychological test scores are not consistently associated with SCT. It remains to be determined if neuropsychological tests can be developed to measure and further our understanding of SCT.