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.