Background

School children with sickle cell anemia (SCA) score significantly lower on executive functioning tasks involving attention, inhibition, working memory, and processing speed. There has been limited research on the impact of SCA on the executive development of preschool-age children, although recent intervention studies have shown that executive functions are trainable at this early age. Emerging research suggests that executive functioning deficits are detectable in the preschool years in the correct assessment setting. We hypothesized that, in addition to an effect of family environment, children with more severe disease factors, i.e. low hemoglobin, transcranial doppler (TCD) velocities, and more hospital admissions, would perform poorly on executive functioning tasks.

Method

Ethical approval was obtained from the local National Health Service (NHS) committee. Children with homozygous SCA (HbSS), aged 36-72 months, without co-morbid disorders or history of stroke, were recruited and underwent the Weschler Preschool and Primary Scale of Intelligence (WPPSI), and the National Institutes of Health (NIH) toolbox tasks of executive functioning, including the flanker inhibition control and attention test and the pattern comparison processing speed test. They also completed behavioral tasks including scrambled boxes for working memory and picture deletion for selective attention/inhibition. Parents completed the Children’s Behavior Questionnaire (CBQ) and the Family Environment Scale (FES). A group of typically developing comparison children was also recruited.

Results

Eight children with SCA (4m: 4f; mean age=4.87 years, range=3.58-5.91) and 23 age-matched comparison children participated. In SCA, no associations were found with hemoglobin and performance on neuropsychological tasks or parent reports of behavior. There were trends for associations between TCD velocities and processing speed on the NIH picture comparison task (r=.769, p=.074, N=6),and number of admissions in the past year and performance IQ (r=-.68, p=.06, N=8) and parent-reported levels of attentional focusing (r=-.68, p=.06, N=8). Parent-reported levels of FES family cohesion were related to TCD velocity (r=.92, p=.01, N=6), and NIH toolbox processing speed (r=.86, p=.03, N=6). Greater emphasis on parent-reported FES active–recreational events correlated with FSIQ (r=.78, p=.039, N=7) and working memory (r=.82, p=.025, N=7). No associations or trends were observed between FES family cohesion and processing speed (N=15) or FES active-recreational and FSIQ (N=23)/working memory (N=14) in a comparison group of typically developing children. Inhibition and attention, as measured by the NIH toolbox test and the picture deletion task, were not related to disease-related or family functioning factors in children with SCA but parent reports of activity level and inhibition were related to performance on the picture deletion task. CBQ activity levels and PDTP commissions were also found to be associated (r=.896, p=.006, N=7) as well as CBQ inhibition and PDTP omissions (r= .896, p=.006, N=7).

Conclusion

This preliminary investigation demonstrates that even at this young age, children with SCA can be investigated for deficits in discrete areas of executive functioning. These findings show the potential benefit of neuropsychological assessment in the identification of children who are at a higher risk of future stroke morbidity. This preliminary evidence, particularly the three-way associations between cerebral blood flow velocity, processing speed, and family cohesion, also suggests that early family interventions in young children with SCA could potentially improve school readiness skills and academic performance in the long-term. Executive functioning skills act as a protective factor in academic attainment and may play an important role in combatting the effects of higher rates of school absences that children with SCA often experience.

Disclosures

No relevant conflicts of interest to declare.

Author notes

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Asterisk with author names denotes non-ASH members.