The annual meeting of APSARD is an opportunity to bring experts together to share knowledge and build collaborative relationships for improving research and clinical practice. In a poster, “Neuropsychological Assessment Discriminates ADHD-I from SCT by Parent Report”, Beth Krone, PhD, Anne Claude Bedard, PhD,  Kurt Schulz, PhD, Iliyan Ivanov, MD, Jeffrey Newcorn, MD, and research assistants Logan Downes, Quinn Downes, Amanda Kirschenbaum, presented an exciting (although relatively weak) double dissociation finding that suggests parent report measures of ADHD and SCT may map onto objective measures of qualitatively, and subtly, different clinical features of attention problems.

Prior research presented by this team at APSARD has examined the construct of Sluggish Cognitive Tempo (SCT). First, the team presented an examination of the SCT construct in a two-site clinical trial of N=235 youth, of whom greater than 60% had clinically significant SCT as measured by the Child Behavior Checklist (CBCL). The CBCL provides T scores according to gender and age norms for SCT behaviors. To test the validity of the CBCL reports, the investigators also collected reports of SCT behaviors from other scales used to characterize their cohort. While there was a trend toward greater across-scale reporting among parents of youth with ADHD-Inattentive presentation than ADHD-Combined type, the additive value of the additional symptom measures was small. Next, the team analyzed latent constructs that contributed to SCT reports among the cohort, and found two separate constructs that contributed to high SCT ratings: a depressive/anxious construct; and a somatic complaints construct.

In further research, the team examined the SCT’s influence on medication treatment response. The team’s findings were consistent with the body of literature stating that higher SCT scores correlate to greater functional impairment, and greater variability in treatment response, less improvement of ADHD with treatment. The treatment effect in this team’s study was attenuated by non-stimulants as compared to stimulants.

The new research being presented by this team examines the neuropsychological correlates of the SCT construct within ADHD by comparing N=107 youth with ADHD and N=30 healthy youth who completed both the Conner’s Continuous Performance Test (CPT-II) and the Attention Networks Test (ANT). The CPT-II is a norm-reference clinical task that assesses attention problems in ADHD, and the most common and consistent finding across ADHD cohorts has been a high variability of performance, yielding high scores for Hit-Rate Standard-Error, and Variability measures. The ANT is a well-validated research measure that has been used extensively to map attention networks among youth with and without ADHD. The ANT provides three network scores: one for attentional alerting; one for orienting attention; and one for executive control. This team hypothesized that SCT’s characteristic sluggishness might best be categorized as a deficit in altering.

Results: The double dissociation of ADHD and SCT was significant, but not particularly strong, with ANT Alerting accounting for about 8% of the variance in SCT reports. However, ANT Alerting (and no other ANT score) associated with ADHD scores. CPT-II measures of performance relating to fluctuations in attention accounted for between 7% and 10% of the variance in ADHD reports, but no CPT-II measure is associated with SCT reports.

Conclusions: This research shows that SCT and ADHD attention problems can each be assessed using different well-validated objective measures of attention. However, the SCT construct within ADHD is far from explained by these differences in neuropsychological testing. Given the strong two-latent class factor structure (factor 1 = depression/anxiety and factor 2 = somatic (physical) illness) associated with SCT in prior analyses, and given the conceptual similarities between SCT symptoms and those of the cytokine mediated sickness response, the team’s hopes to further examine inflammatory biomarkers within the ADHD population. Our hypothesis is that, for a larger portion of the ADHD population, SCT may be a clinical indicator of inflammatory processes either as a prodrome of depressive disorders, or associated with atopic illnesses so common among the ADHD population.