Cognitive/Academic/Executive Functioning and Medical Variables
There were no statistically significant differences found between more severe subtypes (Hemoglobin SS or Hemoglobin Beta 0) and less severe types of SCD (Hemoglobin SC or Hemoglobin Beta +) in terms of mean cognitive score, mean academic score, or parent-reported global executive functioning. Mean cognitive scores, cognitive subtest variance, cognitive subtest range, and mean academic scores were not related to overall hemoglobin, sickle hemoglobin, or fetal hemoglobin levels that were taken +/- 45 days of testing, nor were mean cognitive or academic score related to TCD right or left MCA velocities; though of note, all study participants with a TCD (n = 40) had results in the normal range. Patients with mean academic scores 1 SD below the mean demonstrated marginally significant differences in left MCA velocity (t (37) = -1.82, p = .076). There was a significant, positive association between mean corpuscular volume (MCV) and mean cognitive score (r = .29, p = .03), but not between MCV and academic performance; however, patients with mean academic scores 1 SD or below the mean had lower mean MCV (t(53) = 2.66, p = .01). None of the medical variables assessed demonstrated positive associations with auditory attention scaled scores on the NEPSY-II. Similarly, neither hemoglobin nor MCV were significantly correlated with emotional, cognitive, or behavioral regulation T-scores on the BRIEF-2 or with inattention or hyperactivity T-scores on the Conners-3. Of note, there was a significant correlation found between MCV and both parent (r = .28, p = .05) and self-reported (r = .45, p = .001) psychosocial health summary, but not the physical health summary, on the PedsQL. Neither cognitive nor academic functioning were correlated with parent or child reports of pain on the PedsQL.