Introduction
Sickle cell disease (SCD) is a genetic blood disorder affecting approximately 100,000 individuals in the United States1,2. Primary complications include acute and chronic pain, infection, and silent and overt stroke3. SCD is also associated with neurocognitive impairment. Compared to healthy peers, children with SCD demonstrate deficits in intellectual functioning, verbal abilities, visual-motor and visual-spatial skills, attention and executive functioning including working memory, and processing speed4–9.
Neurocognitive deficits in children with SCD disease are associated with chronic anemia 5,10,11, hypoxemia, and cerebrovascular ischemia9,12,13. While direct neurological insults are associated with a decline in neurocognitive performance14, even children without magnetic resonance imaging (MRI) abnormalities demonstrate lower intellectual functioning skills than healthy controls15. In another study, participants’ neuropsychological performance and imaging abnormalities were not directly related, but abnormal imaging was associated with variability in cognitive performance16. Transcranial doppler (TCD) velocities were predictive of syntactical skills after controlling for anemia severity17, and there is evidence for a relationship between TCD velocity and both visual spatial and perceptual reasoning11.
In line with neurocognitive deficits, academic underachievement is common for children with SCD9,18,19. Approximately 60% of children with SCD report academic difficulties related to their disease20. Academic deficits in SCD are associated with overt and silent stroke13,18,21, and school absenteeism22,23. Likely related to increased school absenteeism over the lifespan, academic problems also seem to increase over time24.
Socioeconomic status (SES) also impacts cognitive and academic functioning in children with SCD. Researchers have identified a relationship between SES and full-scale IQ, language and verbal reasoning, visual spatial and perceptual reasoning, and executive functioning11, as well as between lower SES and increased academic difficulties in children with SCD18,24. In addition, increased parenting stress germane to low SES is associated with less responsive parenting, which in turn was associated with lower cognitive functioning in children25.
Routine screening is thus recommended to assess for cognitive and academic concerns in children with SCD6,22, and our institution instituted a neurocognitive screening program in 2017. This paper describes the outcomes of these evaluations, with screening methodology and referral outcomes more explicitly discussed in a separate manuscript (in preparation). The primary aim of this study was to describe the neurocognitive and academic functioning in children with SCD and explore how functioning might vary by a function of medical variables, psychosocial factors, and age. We hypothesized that neurocognitive and academic functioning in children with SCD would be lower than ex and demonstrate a direct relationship with hemoglobin and TCD velocity, consistent with prior research. We also hypothesized that SES and psychosocial factors would have both a direct and indirect impact on neurocognitive and academic performance.