Sluggish cognitive tempo: Association with neuropsychological test scores, motor incoordination, and dysgraphia in elementary school children

Research on the relationship between sluggish cognitive tempo (SCT) and scores on neuropsychological tests (such as those measuring processing speed and reaction time) is inconclusive, and the association between SCT and motor incoordination and dysgraphia has not been objectively investigated. Mothers of 413 elementary school children (6-12 years of age) rated their children on the Pediatric Behavior Scale (PBS), which yields psychological problem scores, including SCT. Children were administered an extensive battery of neuropsychological tests assessing processing and performance speed, working memory, immediate and delayed recall, sustained attention, response inhibition, cognitive flexibility, fine motor manipulative skill, verbal fluency and retrieval, set shifting, and interference control, as well as intelligence and reading and math achievement. Only three of the 19 correlations between SCT and neuropsychological scores were significant, and all involved graphomotor tests (two timed and one untimed). In regression analysis, the strongest independent predictor of SCT was the maternal PBS incoordination factor score, followed by ratings of autism, inattention, and depression. Neuropsychological test scores did not contribute significantly more to predicting SCT. Among the incoordination PBS factor items, clumsy and draws or writes poorly were significant SCT predictors. Our novel and unexpected findings showed that motor incoordination was a stronger correlate of SCT than other variables assessed in our study, including those previously linked with SCT. Future SCT research needs to include measures of incoordination and dysgraphia in order to replicate and expand upon the current findings. Our results suggest that SCT traits are not reliably measured by currently available neuropsychological tests.