Neuropsychologic performance in school-aged children with sickle cell disease: a report from the Cooperative Study of Sickle Cell Disease

Cognitive Functioning and Educational Support Plans in Youth With Sickle Cell Disease

Children with sickle cell disease (SCD) face academic challenges because of direct and indirect disease-related events. This study examined the proportion of youth with SCD with educational plans and whether cognitive functioning is associated with educational support. Ninety-one youth (7 to 16 y) with SCD completed the WISC-V; caregivers reported educational support (504 Plan/Individualized Education Program) and completed the Behavior Rating Inventory of Executive Function. χ2 square and t test analyses explored whether overall intelligence (full-scale intelligence quotient [FSIQ]), relative weaknesses in processing speed and working memory (> 1SD below FSIQ), and parent-reported executive functioning were associated with educational plans. Participants with a FSIQ<90 were more likely to have support (74%) compared with youth with a FSIQ≥90 (47%; P=0.012). Those with FSIQ≥90 and FSIQ=80 to 89 were less likely to have support (47%, 58%, respectively) compared with those with FSIQ≤79 (89%; P=0.004). Relative weaknesses in processing speed were associated with educational support (83% vs. 52%, P=0.018) as well as behavioral aspects of executive functioning (Ps<0.05). Despite universal eligibility for a 504 Plan, 42% of youth with SCD in our sample did not have educational support. Significant deficits in intellectual functioning, processing speed, and parent-observed executive functioning are associated with having a plan, but children with subtle deficits seem less likely to be identified for educational support.

Cognitive Correlates of Math Performance in School-Aged Children with Sickle Cell Disease and Silent Cerebral Infarcts

OBJECTIVE

Attention, processing speed, executive functioning, and math difficulties are common in youth with sickle cell disease (SCD) with silent cerebral infarcts (SCI). This study investigated the cognitive underpinnings of math difficulties in children with SCD and SCI.

METHOD

Youth (n = 68) with SCD and SCI completed measures of attention [Digit Span forward (DSF); Conners Continuous Performance Test-Third Edition/Kiddie Conners Continuous Performance Test-Second Edition (CPT-3/KCPT-2)]; working memory [Wechsler Intelligence Scales (WPPSI-IV, WISC-IV, WISC-V, WAIS-IV), Working Memory Index (WMI), Digit Span backwards (DSB)]; processing speed [WPPSI-IV, WISC-IV, WISC-V, WAIS-IV Processing Speed Index (PSI)]; math reasoning [Wechsler Individual Achievement Test-Third Edition (WIAT-III) Mathematics composite (MC)]; and math fluency [WIAT-III Math Fluency composite (MF)] as part of a clinical neuropsychological evaluation. Parent ratings of attention and executive functioning were obtained [Behavior Assessment System for Children-Third Edition (BASC-3), Behavior Rating Inventory of Executive Function (BRIEF)].

RESULTS

MC was positively correlated with WMI (r = 0.59, p = 0.00), PSI (r = 0.40, p < 0.001), DSF (r = 0.29, p = 0.03), DSB (r = 0.47, p < 0.001), and MF (r = 0.71, p < 0.001). Correlations between MC, sustained attention, and parent ratings were nonsignificant. The linear regression model using correlated variables was significant [F(4,51) = 8.29, R2 = 0.39, p < 0.001]. WMI was the only significant variable within the model (p = 0.02).

CONCLUSIONS

Working memory deficits account for significant variance in untimed mathematical performance in this population-consistent with other populations with white matter dysfunction. Interventions targeting both mathematics and working memory may be beneficial.

Advances in neuroimaging to improve care in sickle cell disease

Sickle cell disease is associated with progressive and increased neurological morbidity throughout the lifespan. In people with sickle cell anaemia (the most common and severe type of sickle cell disease), silent cerebral infarcts are found in more than a third of adolescents by age 18 years and roughly half of young adults by age 30 years, many of whom have cognitive impairment despite having few or no conventional stroke risk factors. Common anatomical neuroimaging in individuals with sickle disease can assess structural brain injury, such as stroke and silent cerebral infarcts; however, emerging advanced neuroimaging methods can provide novel insights into the pathophysiology of sickle cell disease, including insights into the cerebral haemodynamic and metabolic contributors of neurological injury. Advanced neuroimaging methods, particularly methods that report on aberrant cerebral blood flow and oxygen delivery, have potential for triaging patients for appropriate disease-modifying or curative therapies before they have irreversible neurological injury, and for confirming the benefit of new therapies on brain health in clinical trials.

Academic Challenges and School Service Utilization in Children with Sickle Cell Disease

OBJECTIVES

To describe the academic concerns and risk strata of children with sickle cell disease (SCD) as identified through a parent-directed screening tool and to compare the rates of these concerns with actual school service utilization in the clinic population.

STUDY DESIGN

We completed a retrospective review of patients with SCD referred to the school intervention program during the 2017-2018 and 2018-2019 school years because of a school-related concern raised by parents or noted by the clinical team. All parents completed the Brief School Needs Inventory (BSNI), a validated parent-response tool used to stratify academic risk. Rates of special education services, grade retention, and results from neuropsychologic testing were captured. Clinical history, the use of disease-modifying therapy, and results from laboratory and neuroimaging studies were also obtained. Descriptive statistics were performed to examine demographic information, clinical history, and BSNI results.

RESULTS

In total, 137 unique patients (age range, 14 months to 19 years) completed the BSNI during the study period, for 181 events. According to BSNI risk-stratification, 45% of patients were deemed low, 36% moderate, and 19% high academic risk. Over one-half of parents were concerned about their ability to advocate for their child's needs. Despite legal qualification for a Section 504 accommodation plan, only 20% had established plans. Academic concerns were common with 31% of children reporting an individualized education program and 20% with grade retention/remediation.

CONCLUSIONS

Concerns for academic challenges remain high among parents of children with SCD; however, school service utilization remains disproportionately low attributable to numerous reasons.

Cognitive performance as a predictor of healthcare transition in sickle cell disease

Neurocognitive deficits in sickle cell disease (SCD) may impair adult care engagement. We investigated the relationship between neurocognitive functioning and socio-environmental factors with healthcare transition outcomes. Adolescents aged 15-18 years who had neurocognitive testing and completed a visit with an adult provider were included. Transition outcomes included transfer interval from paediatric to adult care and retention in adult care at 12 and 24 months. Eighty adolescents (59% male, 64% HbSS/HbSβ⁰ -thalassaemia) were included. Mean age at adult care transfer was 18·0 (±0·3) years and transfer interval was 2·0 (±2·3) months. Higher IQ (P = 0·02; P_FDR  = 0·05) and higher verbal comprehension (P = 0·008; P_FDR  = 0·024) were associated with <2 and <6 month transfer intervals respectively. Better performance on measures of attention was associated with higher adult care retention at 12 and 24 months (P = 0·009; P_FDR  = 0·05 and P = 0·04; P_FDR  = 0·12 respectively). Transfer intervals <6 months were associated with smaller households (P = 0·02; P_FDR  = 0·06) and households with fewer children (P = 0·02; P_FDR  = 0·06). Having a working parent was associated with less retention in adult care at 12 and 24 months (P = 0·01; P = 0·02 respectively). Lower IQ, verbal comprehension, attention difficulties and environmental factors may negatively impact transition outcomes. Neurocognitive function should be considered in transition planning for youth with SCD.

Sickle cell disease mice have cerebral oxidative stress and vascular and white matter abnormalities

Strokes are feared complications of sickle cell disease (SCD) and yield significant neurologic and neurocognitive deficits. However, even without detectable strokes, SCD patients have significant neurocognitive deficits in domains of learning and memory, processing speed and executive function. In these cases, mechanisms unrelated to major cerebrovascular abnormalities likely underlie these deficits. While oxidative stress and stress-related signaling pathways play a role in SCD pathophysiology, their role in cerebral injury remains unknown. We have shown that Townes and BERK SCD mice, while not having strokes, recapitulate neurocognitive deficits reported in humans. We hypothesized that cognitive deficits in SCD mice are associated with cerebral oxidative stress. We showed that SCD mice have increased levels of reactive oxygen species, protein carbonylation, and lipid peroxidation in hippocampus and cortex, thus suggesting increased cerebral oxidative stress. Further, cerebral oxidative stress was associated with caspase-3 activity alterations and vascular endothelial abnormalities, white matter changes, and disruption of the blood brain barrier, similar to those reported after ischemic/oxidative injury. Additionally, after repeated hypoxia/reoxygenation exposure, homozygous Townes had enhanced microglia activation. Our findings indicate that oxidative stress and stress-induced tissue damage is increased in susceptible brain regions, which may, in turn, contribute to neurocognitive deficits in SCD mice.

Silent cerebral infarcts in patients with sickle cell disease: a systematic review and meta-analysis

BACKGROUND AND PURPOSE

Silent cerebral infarcts (SCIs) are the most common neurological complication in children and adults with sickle cell disease (SCD). In this systematic review, we provide an overview of studies that have detected SCIs in patients with SCD by cerebral magnetic resonance imaging (MRI). We focus on the frequency of SCIs, the risk factors involved in their development and their clinical consequences.

METHODS

The databases of Embase, MEDLINE ALL via Ovid, Web of Science Core Collection, Cochrane Central Register of Trials via Wiley and Google Scholar were searched from inception to June 1, 2019.

RESULTS

The search yielded 651 results of which 69 studies met the eligibility criteria. The prevalence of SCIs in patients with SCD ranges from 5.6 to 80.6% with most studies reported in the 20 to 50% range. The pooled prevalence of SCIs in HbSS and HbSβ⁰ SCD patients is 29.5%. SCIs occur more often in patients with the HbSS and HbSβ⁰ genotype in comparison with other SCD genotypes, as SCIs are found in 9.2% of HbSC and HbSβ⁺ patients. Control subjects showed a mean pooled prevalence of SCIs of 9.8%. Data from included studies showed a statistically significant association between increasing mean age of the study population and mean SCI prevalence. Thirty-three studies examined the risk factors for SCIs. The majority of the risk factors show no clear association with prevalence, since more or less equal numbers of studies give evidence for and against the causal association.

CONCLUSIONS

This systematic review and meta-analysis shows SCIs are common in patients with SCD. No clear risk factors for their development were identified. Larger, prospective and controlled clinical, neuropsychological and neuroimaging studies are needed to understand how SCD and SCIs affect cognition.

Neurocognitive functioning in long-term survivors of pediatric hematopoietic cell transplantation

Survivors of pediatric hematopoietic cell transplantation (HCT) are at risk for impairment in cognitive and academic function. Most research to date has focused on the first years following transplant, and less is known about the long-term effects. We examined global and specific neurocognitive functioning in long-term (>5 years post HCT) survivors in comparison to both normative data and a sample of demographically similar healthy peers. A comprehensive battery of neurocognitive measures was obtained from 83 long-term survivors and 50 healthy comparisons. Analyses were conducted to assess for differences in neurocognitive functions between survivors, normative means, and healthy comparisons, and to examine the impact of medical and demographic variables on neurocognitive performance. Survivors' performance was within the Average range across most measures, although significantly lower than both test norms and healthy comparisons on several measures. Despite generally intact neurocognitive functioning in the survivor group as a whole, survivors who experienced graft-vs.-host disease demonstrated slower processing speed and weaker verbal learning. Use of total body irradiation was not associated with any performance-based measure of neurocognitive functioning. Although subgroups of patients may be at relatively higher risk of neurocognitive impairment, the long-term neurocognitive impact for most survivors is relatively small.

Functional Connectivity Decreases with Metabolic Stress in Sickle Cell Disease

OBJECTIVE

Children with sickle cell disease (SCD) experience cognitive deficits even when unaffected by stroke. Using functional connectivity magnetic resonance imaging (MRI) as a potential biomarker of cognitive function, we tested our hypothesis that children with SCD would have decreased functional connectivity, and that children experiencing the greatest metabolic stress, indicated by elevated oxygen extraction fraction, would have the lowest connectivity.

METHODS

We prospectively obtained brain MRIs and cognitive testing in healthy controls and children with SCD.

RESULTS

We analyzed data from 60 participants (20 controls and 40 with sickle cell disease). There was no difference in global cognition or cognitive subdomains between cohorts. However, we found decreased functional connectivity within the sensory-motor, lateral sensory-motor, auditory, salience, and subcortical networks in participants with SCD compared with controls. Further, as white matter oxygen extraction fraction increased, connectivity within the visual (p = 0.008, parameter estimate = -0.760 [95% CI = -1.297, -0.224]), default mode (p = 0.012, parameter estimate = -0.417 [95% CI = -0.731, -0.104]), and cingulo-opercular (p = 0.009, parameter estimate = -0.883 [95% CI = -1.517, -0.250]) networks decreased.

INTERPRETATION

We conclude that there is diminished functional connectivity within these anatomically contiguous networks in children with SCD compared with controls, even when differences are not seen with cognitive testing. Increased white matter oxygen extraction fraction was associated with decreased connectivity in select networks. These data suggest that elevated oxygen extraction fraction and disrupted functional connectivity are potentially presymptomatic neuroimaging biomarkers for cognitive decline in SCD. ANN NEUROL 2020;88:995-1008.

Validation of the fine motor subtest of the Bayley-III with children with sickle cell disease using Rasch analysis

BACKGROUND

Children with sickle cell disease (SCD) are at risk for fine motor (FM) delays; however, screening for FM impairments is not common among young children with SCD. The Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III) is the most commonly used performance-based developmental assessment. We aim to determine if the FM subtest of the Bayley-III is structured hierarchically in accordance with development and comprehensively evaluates FM development in children with SCD.

METHODS

Bayley-III assessments were completed between October 2009 and December 2013. The Bayley-III FM screening test, a shorter and more rapid method of assessing for FM impairments, was not directly administered to participants. Screening test scores were calculated from full Bayley-III scores.

RESULTS

Rasch analysis was performed using WINSTEPS. Sixty children with SCD were included in the final Rasch model. The Rasch-generated Wright map, which jointly positions items and persons on the same latent trait, illustrated that the FM items were slightly skewed towards more challenging items, indicating more difficult items may be overrepresented. High item separation values were reported (17.4), and item outfit statistics were less than 1.7. More than one third of items demonstrated overfit, indicating possible item redundancy. The FM subtest and the screening test, a shorter and faster method of assessing skills, were highly correlated (r = 0.993, p < 0.001).

CONCLUSION

The Bayley-III FM subtest is structured hierarchically, aligning with motor development, and comprehensively evaluates FM development in children with SCD. The test could be improved by reordering items, removing overfitting items and modifying screening test items to capture all ranges of development. The screening test is comprehensive and has high potential clinical utility among children with SCD.

Locomotor mal-performance and gait adaptability deficits in sickle cell mice are associated with vascular and white matter abnormalities and oxidative stress in cerebellum

Patients with sickle cell disease (SCD) can develop strokes and as a result, present neurologic and neurocognitive deficits. However, recent studies show that even without detectable cerebral parenchymal abnormalities on imaging studies, SCD patients can have significant cognitive and motor dysfunction, which can present as early as during infancy. As the cerebellum plays a pivotal role in motor and non-motor functions including sensorimotor processing and learning, we examined cerebellar behavior in humanized SCD mice using the Erasmus ladder. Homozygous (sickling) mice had significant locomotor malperformance characterized by miscoordination and impaired locomotor gait/stepping pattern adaptability. Conversely, Townes homozygous mice had no overall deficits in motor learning, as they were able to associate a conditioning stimulus (high-pitch warning tone) with the presentation of an obstacle and learned to decrease steptimes thereby increasing speed to avoid it. While these animals had no cerebellar strokes, these locomotor and adaptive gait/stepping patterns deficits were associated with oxidative stress, as well as cerebellar vascular endothelial and white matter abnormalities and blood brain barrier disruption, suggestive of ischemic injury. Taken together, these observations suggest that motor and adaptive locomotor deficits in SCD mice mirror some of those described in SCD patients and that ischemic changes in white matter and vascular endothelium and oxidative stress are biologic correlates of those deficits. These findings point to the cerebellum as an area of the central nervous system that is vulnerable to vascular and white matter injury and support the use of SCD mice for studies of the underlying mechanisms of cerebellar dysfunction in SCD.

Cerebral Infarcts and Vasculopathy in Tanzanian Children With Sickle Cell Anemia

BACKGROUND

Cerebral infarcts and vasculopathy in neurologically asymptomatic children with sickle cell anemia (SCA) have received little attention in African settings. This study aimed to establish the prevalence of silent cerebral infarcts (SCI) and vasculopathy and determine associations with exposure to chronic hemolysis, anemia, and hypoxia.

METHODS

We prospectively studied 224 children with SCA with transcranial Doppler (TCD), and magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA). Regressions were undertaken with contemporaneous hemoglobin, reticulocyte count, mean prior hemoglobin, oxygen content, reticulocyte count, and indirect bilirubin.

RESULTS

Prevalence of SCI was 27% (61 of 224); cerebral blood flow velocity was abnormal (>200 cm/s) in three and conditional (>170<200 cm/s) in one. Vasculopathy grades 2 (stenosis) and 3 (occlusion) occurred in 16 (7%) and two (1%), respectively; none had grade 4 (moyamoya). SCI was associated with vasculopathy on MRA (odds ratio 2.68; 95% confidence intervals [95% CI] 1.32 to 5.46; P = 0.007) and mean prior indirect bilirubin (odds ratio 1.02, 95% CI 1.00 to 1.03, P = 0.024; n = 83) but not age, sex, non-normal TCD, or contemporaneous hemoglobin. Vasculopathy was associated with mean prior values for hemoglobin (odds ratio 0.33, 95% CI 0.16 to 0.69, P = 0.003; n = 87), oxygen content (odds ratio 0.43, 95% CI 0.25 to 0.74, P = 0.003), reticulocytes (odds ratio 1.20, 95% CI 1.01-1.42, P = 0.041; n = 77), and indirect bilirubin (odds ratio 1.02, 95% CI 1.01 to 1.04, P = 0.009).

CONCLUSIONS

SCI and vasculopathy on MRA are common in neurologically asymptomatic children with SCA living in Africa, even when TCD is normal. Children with vasculopathy on MRA are at increased risk of SCI. Longitudinal exposure to anemia, hypoxia, and hemolysis appear to be risk factors for vasculopathy.

A pilot study to screen for poor academic performance in children with sickle cell disease in the outpatient setting

BACKGROUND

Children with sickle cell disease (SCD) are at risk for neurocognitive deficits, which can lead to effects on academic performance and later job attainment. However, screening in children at high risk for poor academic performance (PAP) in a clinic setting has been limited. The goal was to identify young children with SCD at high risk for PAP via administration of a standardized screening tool at the clinic visit.

PROCEDURE

Parents of 20 patients were asked to complete the Behavior Assessment System for Children, 3rd edition (BASC-3) Parent Rating Scale. Children ages six to nine years and all SCD genotypes were included. Those patients who scored at least 1 standard deviation below the mean were considered high risk. Statistics was used to associate demographic, academic, and laboratory data with risk status (RS).

RESULTS

Four of 20 patients (20%) were found to be at risk by the BASC-3. A significant association was found between those with a history of PAP and RS (P = 0.001). A trend toward association was found between baseline hemoglobin, reticulocyte count, and RS. Children not at risk had a higher hemoglobin level and lower reticulocyte count (P = 0.37 and P = 0.20, respectively). Those on hydroxyurea were significantly less likely to score as at risk (P = 0.014), whereas those with siblings may be at greater risk (P = 0.037).

CONCLUSION(S)

A parent-directed screening tool may identify children with SCD in need of additional school support. Further prospective studies are necessary to understand correlations found between hemoglobin, reticulocyte count, and hydroxyurea treatment and risk for PAP.

Patient and family experience with chronic transfusion therapy for sickle cell disease: A qualitative study

Background

There is a limited understanding of the patient and family experience of Chronic Transfusion Therapy (CTT) for prevention of complications of Sickle Cell Disease (SCD). We sought to understand patient and family experience with CTT using qualitative methods.

Methods

Fifteen parents of children < 18 years old and nine children 12–18 years old with SCD who were receiving CTT for > 1 year were interviewed using a semi-structured interview format, and interviews were analyzed using open coding methods.

Results

Four themes created a narrative of the patient and family experience of CTT: 1) Burden of CTT, 2) Coping with CTT, 3) Perceived benefits and risks of CTT, and 4) Decision making regarding CTT. Participants reported substantial burden of CTT, including the impact of CTT on daily life and family, distress about venous access, burden of chelation therapy, and anxiety about CTT complications. Participants described how they coped with CTT. Participants reported increased energy, decreased pain, fewer hospitalizations, and stroke prevention with CTT, but also recognized complications of CTT, though awareness was limited in adolescents. Parents described sharing in the informed decision-making process with their healthcare provider about CTT, but adolescent patient participants reported that they were not involved in this process.

Conclusions

CTT is associated with significant patient and family burden. Support from family, healthcare providers and school may help individuals cope with some of this burden. These findings provide the basis for future studies to identify strategies to mitigate the burden of CTT and improve the patient experience with this therapy. Future studies should also systematically assess patient knowledge about the key components of CTT and chelation using quantitative assessments.

What is the place of hematopoietic stem cell transplantation in the management of cerebral vasculopathy in children with sickle cell anemia?

Cerebral vasculopathy is the most severe complication affecting children with sickle cell anemia. Significant progress has been made in the management of sickle cell anemia cerebral vasculopathy, including early transcranial Doppler screening, chronic transfusion, andhydroxyurea. Nevertheless, for patients with a potential matched-sibling donor (MSD), stem cell transplantation (SCT) is now the treatment offering the best cerebral vasculopathy outcome. In the absence of MSD,alternative SCT should be recommended only in those with worsening cerebral vasculopathy despite standard treatments, and should be limited to related haplo-identical SCT undertaken in controlled studies.

White Matter Integrity in Tanzanian Children With Sickle Cell Anemia: A Diffusion Tensor Imaging Study

Background and Purpose- Widespread reductions in white matter integrity are associated with cognitive dysfunction in sickle cell anemia. Silent cerebral infarction (SCI), vasculopathy (VSC), and low hemoglobin concentration (Hb) are implicated; we aimed to determine independent contributions to microstructural white matter injury and whether white matter integrity differs across arterial territories. Methods- Sixty two children with sickle cell anemia aged 6 to 19 years were prospectively studied at Muhimbili National Hospital, Tanzania. SCI± and VSC± were identified on magnetic resonance imaging (MRI)/magnetic resonance angiography (MRA) scans by 2 neuroradiologists. Tract-based spatial statistics tested for voxel-wise differences in diffusion tensor imaging metrics (ie, fractional anisotropy, mean diffusivity, radial diffusivity, and axial diffusivity) between SCI± and VSC± groups, with correlations between diffusion tensor imaging metrics and Hb. In tract-based spatial statistics analyses, potentially mediating factors (ie, age, sex, as well as Hb, SCI, and/or vasculopathy) were covariates. Differences in mean diffusion tensor imaging metrics across regions of interest in arterial territories were explored. Results- Compared with SCI- patients (n=45), SCI+ patients (n=17) exhibited increased radial diffusivity in multiple regions; negative relationships were observed between mean diffusivity, axial diffusivity, and Hb (P<0.005). Compared with VSC- patients (n=49), mild (n=6) or moderate (n=7) VSC+ patients exhibited reduced fractional anisotropy in widespread regions (P<0.05) including the anterior longitudinal fasciculi, corpus callosum, internal capsule, corona radiata, and corticospinal tracts. Overall, the posterior cerebral arterial territory had higher mean mean diffusivity and mean radial diffusivity than the anterior and middle cerebral arterial territories, although no patient had vasculopathy in this area. There was an interaction between territory and vasculopathy. Conclusions- SCI, vasculopathy, and Hb are independent risk factors, and thus treatment targets, for diffuse white matter injury in patients with sickle cell anemia. Exacerbation of hemodynamic stress may play a role.

Laboratory Biomarkers, Cerebral Blood Flow Velocity, and Intellectual Function in Children with Sickle Cell Disease

Objective

The aim of this preliminary study was to describe putative markers of cerebral vasculopathy and investigate relationships among these markers, demographic factors, and cognitive function in a young sample of neurologically normal children with SCD. Study Design. Thirty-eight children with homozygous HbS, aged 4-11 years, were included. Estimated IQ and markers of coagulation and endothelial activation, hemolysis, and inflammation, as well as transcranial Doppler velocities, hydroxyurea use, and demographic information were obtained.

Results

Using multiple regression analyses, there were few significant independent associations between biomarkers or blood flow velocity and estimated IQ. Lactic dehydrogenase (LDH) independently predicted cognitive function, but blood flow velocity did not mediate this relationship. Maternal education, patient age, and hydroxyurea status were independent predictors of cognition. Given the small sample size, a LASSO statistical model was employed to further identify potential predictors of IQ, which identified LDH, absolute neutrophil count (ANC), platelet count, thrombin-antithrombin (TAT), tissue factor (TF), maternal education, age, and hydroxyurea as potential predictors of cognition.

Conclusions

In addition to effects of age and maternal education, some vasculopathic markers are associated with cognitive function in young children with SCD, and these relationships do not appear to be mediated through blood flow velocity. Although the lack of association among certain variables was not as predicted, results provide support for further research regarding the influence of vasculopathic markers on cognitive function in children with SCD without stroke, especially intravascular hemolysis and coagulation/endothelial activation, and a possible role for HU treatment in preventing or reversing cognitive decline.

Association between hydroxycarbamide exposure and neurocognitive function in adolescents with sickle cell disease

Patients with sickle cell disease (SCD) are at increased risk for neurocognitive impairments. While disease-modifying treatment, such as hydroxycarbamide (hydroxyurea), may decrease this risk, it has not been systematically investigated in children with SCD. We screened neurocognitive functioning in 103 adolescents with SCD (16-17 years, 50% female) and compared outcomes between patients with a history of exposure to hydroxycarbamide (n = 12 HbSC/HbSβ⁺ thalassaemia; n = 52 HbSS/HbSβ⁰ thalassaemia) and those never treated with hydroxycarbamide (n = 31 HbSC/HbSβ⁺ thalassaemia; n = 8 HbSS/HbSβ⁰ thalassaemia). Demographic distributions were similar between the groups. After adjusting for socioeconomic status, the hydroxycarbamide group had significantly higher scores on nonverbal IQ (HbSC/HbSβ thalassaemia: P = 0·036, effect size [d] = 0·65), reaction speed (HbSS/HbSβ⁰ thalassaemia: P = 0·002, d = 1·70), sustained attention (HbSS/HbSβ⁰ thalassaemia: P = 0·014, d = 1·30), working memory (HbSC/HbSβ⁺ thalassaemia: P = 0·034, d = 0·71) and verbal memory (HbSC/HbSβ⁺ thalassaemia: P = 0·038, d = 0·84) when compared to those who did not receive hydroxycarbamide. In patients with HbSS/HbSβ⁰ thalassaemia, longer treatment duration with hydroxycarbamide was associated with better verbal memory (P = 0·009) and reading (P = 0·002). Markers of hydroxycarbamide effect, including higher fetal haemoglobin (HbF), higher mean corpuscular volume (MCV) and lower white blood cell count (WBC), were associated with better verbal fluency (HbF: P = 0·014, MCV: P = 0·006, WBC: P = 0·047) and reading (MCV: P = 0·021, WBC: P = 0·037). Cognitive impairment may be mitigated by exposure to hydroxycarbamide in adolescents with SCD.

Ischemic sequelae and other vascular diseases

Although pediatric stroke is associated with higher survival rates compared with adult stroke, a substantial body of evidence indicates significant neuropsychologic morbidity in pediatric stroke survivors. Neuroplasticity does not guarantee good outcome in children. The general trends observed in the literature are reviewed as is the profile observed in common causes of pediatric stroke: congenital heart disease, moyamoya disease, and sickle cell disease. The neuropsychologic profile of pediatric stroke patients is heterogeneous due to the multiplicity of associated causes. Stroke in early infancy and large strokes are associated with cognitive impairment while more limited disorders, such as phasic deficit, are observed in childhood stroke. Executive dysfunction is common in pediatric stroke, but social interaction skills are usually preserved. Congenital heart disease and sickle cell disease are associated with global neuropsychologic dysfunction while cognition is usually preserved in moyamoya. Executive dysregulation is instead more frequently reported in this population. Further study of maladaptive processes after pediatric stroke will allow identification of predictors of functional and neuropsychologic outcomes and permit personalization of care.

Anemia predicts lower white matter volume and cognitive performance in sickle and non-sickle cell anemia syndrome

Severe chronic anemia is an independent predictor of overt stroke, white matter damage, and cognitive dysfunction in the elderly. Severe anemia also predisposes to white matter strokes in young children, independent of the anemia subtype. We previously demonstrated symmetrically decreased white matter (WM) volumes in patients with sickle cell disease (SCD). In the current study, we investigated whether patients with non-sickle anemia also have lower WM volumes and cognitive dysfunction. Magnetic Resonance Imaging was performed on 52 clinically asymptomatic SCD patients (age = 21.4 ± 7.7; F = 27, M = 25; hemoglobin = 9.6 ± 1.6 g/dL), 26 non-sickle anemic patients (age = 23.9 ± 7.9; F = 14, M = 12; hemoglobin = 10.8 ± 2.5 g/dL) and 40 control subjects (age = 27.7 ± 11.3; F = 28, M = 12; hemoglobin = 13.4 ± 1.3 g/dL). Voxel-wise changes in WM brain volumes were compared to hemoglobin levels to identify brain regions that are vulnerable to anemia. White matter volume was diffusely lower in deep, watershed areas proportionally to anemia severity. After controlling for age, sex, and hemoglobin level, brain volumes were independent of disease. WM volume loss was associated with lower Full Scale Intelligence Quotient (FSIQ; P = .0048; r² = .18) and an abnormal burden of silent cerebral infarctions (P = .029) in males, but not in females. Hemoglobin count and cognitive measures were similar between subjects with and without white-matter hyperintensities. The spatial distribution of volume loss suggests chronic hypoxic cerebrovascular injury, despite compensatory hyperemia. Neurocognitive consequences of WM volume changes and silent cerebral infarction were strongly sexually dimorphic. Understanding the possible neurological consequences of chronic anemia may help inform our current clinical practices.

Why, Who, When, and How? Rationale for Considering Allogeneic Stem Cell Transplantation in Children with Sickle Cell Disease

Considering the progress made in the management of sickle cell disease during the past 30 years, along with the excellent results obtained with hematopoietic stem cell transplantation (SCT), it is important to reexamine why, who, when and how to recommend allogeneic SCT in children with sickle cell disease. While sickle cell disease has a low risk of death in children and a high risk for morbidity during aging, SCT carries an early risk of death, graft-vs-host disease and infertility. Nevertheless, SCT offers at least 95% chance of cure with low risk of chronic graft-vs-host disease when a matched-sibling donor is available and the risks of infertility can be reduced by ovarian, sperm or testis cryopreservation. Thus, all available therapies such as hydroxyurea, transfusions and SCT should be presented to the parents, providers, and affected children and discussed with them from infancy. Furthermore, the use of these therapies should be adjusted to the severity of the disease and to local availabilities in order to choose the treatment offering the best benefit/risk ratio.

The Role of Family Functioning in the Development of Executive Functions in Preschool Children with Sickle Cell Anemia

Executive functions are compromised in children with sickle cell anemia. There is limited research on the development of executive functions in preschool children with sickle cell anemia and the factors that contribute to executive dysfunction. We looked at the relation between biomedical and environmental factors, including family functioning and socioeconomic status, and executive functions in 22 preschool children with sickle cell anemia. We found that family functioning was the strongest predictor of executive outcomes in young children with sickle cell anemia with no evidence for an influence of disease severity at this early stage.

Vascular Instability and Neurological Morbidity in Sickle Cell Disease: An Integrative Framework

It is well-established that patients with sickle cell disease (SCD) are at substantial risk of neurological complications, including overt and silent stroke, microstructural injury, and cognitive difficulties. Yet the underlying mechanisms remain poorly understood, partly because findings have largely been considered in isolation. Here, we review mechanistic pathways for which there is accumulating evidence and propose an integrative systems-biology framework for understanding neurological risk. Drawing upon work from other vascular beds in SCD, as well as the wider stroke literature, we propose that macro-circulatory hyper-perfusion, regions of relative micro-circulatory hypo-perfusion, and an exhaustion of cerebral reserve mechanisms, together lead to a state of cerebral vascular instability. We suggest that in this state, tissue oxygen supply is fragile and easily perturbed by changes in clinical condition, with the potential for stroke and/or microstructural injury if metabolic demand exceeds tissue oxygenation. This framework brings together recent developments in the field, highlights outstanding questions, and offers a first step toward a linking pathophysiological explanation of neurological risk that may help inform future screening and treatment strategies.

Integrated psychology support and comprehensive cognitive evaluation improves access to special education services for children with sickle cell disease

BACKGROUND

Children with sickle cell disease (SCD) are at risk for cognitive deficits. Limited data describe whether comprehensive cognitive evaluation improves education resources and whether caregivers perceive the assessment as beneficial. We tested our two hypotheses: (a) an integrated comprehensive cognitive evaluation program in children with SCD results in increased special education services allocation; and (b) caregivers will value comprehensive cognitive evaluation services provided.

PROCEDURE

In a tertiary care medical facility, as part of quality improvement project, in a before-and-after evaluation between March 2011 and July 2014, we examined the impact of targeted comprehensive cognitive evaluation on change in special education services. We also evaluated the caregiver's perception regarding the utility of the provided services.

RESULTS

A total of 21% (42 of 196) students (median age 11 years, range 3-18) with SCD were referred for cognitive assessment due to overt stroke (n = 11), silent stroke (n = 14), or concerns about cognitive or academic functioning without evidence of strokes (n = 17). At baseline, 45.2% received special education services and after the comprehensive cognitive evaluation 86.7% received special education services (P < 0.001). Among 33 caregivers who completed the survey, 97% reported that the assessment was helpful and 60% indicated that assessment led to beneficial changes for their children at school.

CONCLUSION

Education advocacy coupled with comprehensive cognitive assessment in students with SCD improved access to special education services, and caregivers uniformly endorse this service as having added value.

Cognitive profile of children with sickle cell anemia compared to healthy controls

OBJECTIVE

To evaluate the cognitive abilities of children and adolescents with sickle cell anemia diagnosed through neonatal screening and to compare them with healthy controls, adjusting the results to their socioeconomic status.

METHODS

Cognitive assessment was performed with the Wechsler WISC-III scale in 64 children and adolescents with sickle cell anemia and in 64 controls matched by gender and age, without the disease and without neurological impairment; socioeconomic status was measured by the Criterion Brasil.

RESULTS

All cognitive scores were lower in the group of patients. The mean overall IQ, Verbal IQ, and Performance IQ were, respectively, 90.95 for the group of patients and 113.97 for the controls (p<0.001); 91.41 for the group of patients and 112.31 for the controls (p<0.001); 92.34 for the group of patients and 113.38 for the controls (p<0.001). Scores for processing speed, distraction resistance, and perceptual organization were also significantly lower in patients. A direct and significant correlation was detected between socioeconomic status and cognitive scores. In the multivariate analysis, for the same socioeconomic status, a child with sickle cell anemia had an average IQ of 21.2 points lower than the mean IQ observed for the controls (p<0.001), indicating that the disease, adjusted for the socioeconomic effect, is a strong predictor of the overall IQ.

CONCLUSION

The cognitive impairment of children with sickle cell anemia is severe and manifests even when the disease effect is adjusted to the socioeconomic status. In the authors' view, such impairment requires an early preventive approach in order to avoid this cognitive damage.

Noninvasive optical assessment of resting-state cerebral blood flow in children with sickle cell disease

Sickle cell disease (SCD) is a genetic blood disorder that has profound effects on the brain. Chronic anemia combined with both macro- and microvascular perfusion abnormalities that arise from stenosis or occlusion of blood vessels increased blood viscosity, adherence of red blood cells to the vascular endothelium, and impaired autoregulatory mechanisms in SCD patients all culminate in susceptibility to cerebral infarction. Indeed, the risk of stroke is 250 times higher in children with SCD than in the general population. Unfortunately, while transcranial Doppler ultrasound (TCD) has been widely clinically adopted to longitudinally monitor macrovascular perfusion in these patients, routine clinical screening of microvascular perfusion abnormalities is challenging with current modalities (e.g., positron emission tomography and magnetic resonance imaging) given their high-cost, requirement for sedation in children < 6 year, and need for trained personnel. We assess the feasibility of a low-cost, noninvasive optical technique known as diffuse correlation spectroscopy (DCS) to quantify an index of resting-state cortical cerebral blood flow (BFI) in 11 children with SCD along with 11 sex- and age-matched healthy controls. As expected, BFI was significantly higher in SCD subjects compared to healthy controls ( p < 0.001 ). Within SCD subjects, BFI was inversely proportional to resting-state arterial hemoglobin levels ( p = 0.012 ), consistent with expected anemia-induced compensatory vasodilation that aims to maintain adequate oxygen delivery to the tissue. Further, in a subset of patients measured with TCD ( n = 7 ), DCS-measured blood flow was correlated with TCD-measured blood flow velocity in middle cerebral artery ( R s = 0.68 ), although the trend was not statistically significant ( p = 0.11 ). These results are consistent with those of several previous studies using traditional neuroimaging techniques, suggesting that DCS may be a promising low-cost tool for assessment of tissue-level CBF in pediatric SCD.

Increasing Educational Attainment in Adolescents with Sickle Cell Disease

Adolescents with sickle cell disease (SCD), a chronic condition primarily impacting African Americans, experience challenges graduating high school. Understanding demographic, educational, and community-level correlates of disease is critical to creating effective interventions for these youths. This study aimed to examine 1) educational attainment for adolescents with SCD, 2) neighborhood correlates of their education, and 3) feasibility of a pilot to increase General Education Diploma (GED) class enrollment. Findings suggest demographic characteristics influence educational attainment. Improving educational attainment in adolescents with SCD requires understanding risk beyond disease severity. Identifying risk and protective neighborhood-level factors can inform interventions to improve educational attainment. Feasibility of programming to increase GED enrollment should be further investigated.

Sickle Cell Disease and Stroke

Cerebral infarction is a common complication of sickle cell disease and may manifest as overt stroke or cognitive impairment associated with "silent" cerebral infarction on magnetic resonance imaging. Vasculopathy may be diagnosed on transcranial Doppler or magnetic resonance angiography. The risk factors in sickle cell disease for cognitive impairment, overt ischemic stroke, silent cerebral infarction, overt hemorrhagic stroke, and vasculopathy defined by transcranial Doppler or magnetic resonance angiography overlap, with severe acute and chronic anemia, acute chest crisis, reticulocytosis, and low oxygen saturation reported with the majority. However, there are differences reported in different cohorts, which may reflect age, geographic location, or neuroimaging techniques, for example, magnetic resonance imaging field strength. Regular blood transfusion reduces, but does not abolish, the risk of neurological complications in children with sickle cell disease and either previous overt stroke or silent cerebral infarction or abnormal transcranial Doppler. There are relatively few data on the use of hydroxyurea or other management strategies. Early assessment of the risk of neurocognitive complications is likely to become increasingly important in the management of sickle cell disease.

Hydroxyurea reduces cerebral metabolic stress in patients with sickle cell anemia

Chronic transfusion therapy (CTT) prevents stroke in selected patients with sickle cell anemia (SCA). We have shown that CTT mitigates signatures of cerebral metabolic stress, reflected by elevated oxygen extraction fraction (OEF), which likely drives stroke risk reduction. The region of highest OEF falls within the border zone, where cerebral blood flow (CBF) nadirs; OEF in this region was reduced after CTT. The neuroprotective efficacy of hydroxyurea (HU) remains unclear. To test our hypothesis that patients receiving HU therapy have lower cerebral metabolic stress compared with patients not receiving disease-modifying therapy, we prospectively obtained brain magnetic resonance imaging scans with voxel-wise measurements of CBF and OEF in 84 participants with SCA who were grouped by therapy: no disease-modifying therapy, HU, or CTT. There was no difference in whole-brain CBF among the 3 cohorts (P = .148). However, whole-brain OEF was significantly different (P < .001): participants without disease-modifying therapy had the highest OEF (median 42.9% [interquartile range (IQR) 39.1%-49.1%]), followed by HU treatment (median 40.7% [IQR 34.9%-43.6%]), whereas CTT treatment had the lowest values (median 35.3% [IQR 32.2%-38.9%]). Moreover, the percentage of white matter at highest risk for ischemia, defined by OEF greater than 40% and 42.5%, was lower in the HU cohort compared with the untreated cohort (P = .025 and P = .034 respectively), but higher compared with the CTT cohort (P = .018 and P = .029 respectively). We conclude that HU may offer neuroprotection by mitigating cerebral metabolic stress in patients with SCA, but not to the same degree as CTT.

Student perspectives on managing sickle cell disease at school

OBJECTIVE

The study objective was to identify the perceptions of children with sickle cell disease (SCD) in the school environment.

METHODS

Semistructured interviews (N = 14) were conducted with pediatric patients ages 6 to 10 who attended Metro Nashville Public Schools. These participants were recruited through the Vanderbilt Sickle Cell Disease Clinic. Participants were asked about the perceived efficacy of their teachers to (1) understand SCD; (2) communicate with students regarding SCD; (3) handle an SCD-related pain episode in school; and (4) identify methods to compensate for school absenteeism associated with an SCD diagnosis. Content analysis identified underlying themes.

RESULTS

Five themes emerged that highlighted the perceptions and recommendations of children with SCD in the school environment: (1) perceptions that allow students to prevent SCD from limiting their school experience; (2) administrator actions to alleviate challenges associated with SCD; (3) communication about SCD; (4) how SCD interferes with school activities; and (5) ways students advocate for themselves. Students also provided four areas of recommendations for school personnel: (1) ways teachers can help with school activities; (2) make-up work for school absences; (3) empowering students with SCD; and (4) helping with SCD episodes at school.

CONCLUSIONS

Students with SCD advocated strongly for their needs at school to attain their education. However, they perceived school personnel to lack knowledge about SCD management. This could be overcome with a handbook specific for teachers of students with SCD that could address each of the five themes.

Functional and Radiologic Assessment of the Brain after Reduced-Intensity Unrelated Donor Transplantation for Severe Sickle Cell Disease: Blood and Marrow Transplant Clinical Trials Network Study 0601

Stroke and cognitive decline are hallmarks of sickle cell disease (SCD). The natural history of SCD predicts progressive loss of 1 IQ point per year attributable to disease-related pathology. Hematopoietic cell transplantation (HCT) is curative by reverting to donor-derived erythropoiesis, but evidence that HCT can positively influence disease-induced cognitive decline is lacking. The Sickle Cell Unrelated Transplant Trial prospectively evaluated cognition and brain magnetic resonance imaging (MRI) findings at 2 years after reduced-intensity conditioning followed by unrelated donor HCT. Thirteen study participants completed pre-HCT and post-HCT assessments of intelligence. The mean age of participants was 12.5 ± 3.3 years (range, 6.7 to 17.4 years). Eleven of the 13 recipients completed imaging studies at baseline and post-HCT. Seven had overt stroke pre-HCT, and 1 had an elevated transcranial Doppler velocity with abnormal MRI. The mean Full-Scale IQ was stable: 90.9 ± 13 at baseline and 91.2 ± 13 post-HCT. The mean Performance IQ was 89.9 ± 13 at baseline versus 90.9 ± 13 post-HCT, and mean Verbal IQ was 93.4 ± 13 at baseline versus 93.2 ± 13 post-HCT, respectively. Six recipients had stable MRI; 2 showed resolution of all areas of infarction. Three had additional infarcts post-HCT noted at the 2-year time point. This is the first report describing stabilization of IQ and central nervous system outcomes after unrelated donor HCT despite previous central nervous system morbidity and post-HCT posterior reversible encephalopathy syndrome. These preliminary results post-HCT suggest that HCT may stabilize the cognitive decline of SCD and should continue to be followed over the long term.

Prevalence and nature of hearing loss in a cohort of children with sickle cell disease

BACKGROUND

Sickle cell disease (SCD) may cause injury to any organ, including the auditory system. Although the association of SCD and hearing loss has been described, the nature of this complication is unknown. We sought to establish the prevalence and nature of hearing loss in a referred cohort of children with SCD and to identify correlating disease- or treatment-associated factors.

PROCEDURE

We conducted a retrospective review of patients with SCD < 22 years of age who had hearing evaluations between August 1990 and December 2014. Demographics, audiograms, and disease and treatment variables were analyzed.

RESULTS

Two hundred and ten audiograms among 81 patients were reviewed, and 189 were evaluable. Seventy-two children constituted the referred cohort. Fourteen (19.4%) had hearing loss documented on at least one audiogram. Seven (9.7%) patients had only conductive hearing loss, and the loss persisted for up to 10.3 years. The median age of first identification was eight years. Six (8.3%) patients had hearing loss that was at least partially sensorineural. One patient's hearing loss was ambiguous. All sensorineural hearing losses were unilateral and 4/6 patients had prior documented normal hearing, indicating acquired loss. No correlations were identified.

CONCLUSIONS

Both conductive and sensorineural hearing losses are more prevalent in our study population than those observed in the general pediatric population. In children with SCD, sensorineural hearing loss appears to be acquired and unilateral. Conductive hearing loss was identified in older children and can persist. Serial screening is needed for early detection and more prompt intervention in this population.

Measuring success: utility of biomarkers in sickle cell disease clinical trials and care

Progress in the care of sickle cell disease (SCD) has been hampered by the extreme complexity of the SCD phenotype despite its monogenic inheritance. While epidemiological studies have identified clinical biomarkers of disease severity, with a few exceptions, these have not been routinely incorporated in clinical care algorithms. Furthermore, existing biomarkers have been poorly apt at providing objective parameters to diagnose sickle cell crisis, the hallmark, acute complication of SCD. The repercussions of these diagnostic limitations are reflected in suboptimal care and scarcity of adequate outcome measures for clinical research. Recent progress in molecular and imaging diagnostics has heralded a new era of personalized medicine in SCD. Precision medicine strategies are particularly timely, since molecular therapeutics are finally on the horizon. This chapter will summarize the existing evidence and promising data on biomarkers for clinical care and research in SCD.

Does sickle cell disease have a psychosomatic component? A particular focus on anxiety and depression

Sickle cell disease, an early-age genetic condition, encompasses a range of blood disorders with severe complications. This disease is characterized by the synthesis of abnormal hemoglobin molecules, which tend to polymerize due to their low solubility upon deoxygenation in the peripheral capillary beds, resulting in sickle-like red blood cells. Sickled cells lose their normal functioning and hemodynamic properties, leading to chronic fatigue as well as to episodes of painful crises. Over the last two decades, a growing body of clinical evidence has pointed out that these somatic complaints can give rise to neuropsychiatric disorders, among which anxiety and depression are the most common, that worsen the health-related quality of life in patients. At first glance, this somatic influence may be unsurprising, as both anxiety and depressive signs are prevalent in almost all chronic diseases. However, in the case of a genetic condition such as sickle cell disease whose somatic disturbances are predetermined, the fact that mood disorders can increase fatigue and pain through a psychosomatic component has attracted increasing attention. In this review, we address the hypothesis of a psychosomatic component in patients with sickle cell disease by underlining the most relevant clinical studies that have highlighted the existence of a bidirectional link between physical and psychological sequelae, which are reported to be relieved not only by pharmacological cotreatments but also by the concomitant application of cognitive behavioral therapy.

Sickle Cell Clinical Research and Intervention Program (SCCRIP): A lifespan cohort study for sickle cell disease progression from the pediatric stage into adulthood

BACKGROUND

Previous natural history studies have advanced the understanding of sickle cell disease (SCD), but generally have not included sufficient lifespan data or investigation of the role of genetics in clinical outcomes, and have often occurred before the widespread use of disease-modifying therapies, such as hydroxyurea and chronic erythrocyte transfusions. To further advance knowledge of SCD, St. Jude Children's Research Hospital established the Sickle Cell Clinical Research and Intervention Program (SCCRIP), to conduct research in a clinically evaluated cohort of individuals with SCD across their lifetime.

PROCEDURES

Initiated in 2014, the SCCRIP study prospectively recruits patients diagnosed with SCD and includes retrospective and longitudinal collection of clinical, neurocognitive, geospatial, psychosocial, and health outcomes data. Biological samples are banked for future genomics and proteomics studies. The organizational structure of SCCRIP is based upon organ/system-specific working groups and is opened to the research community for partnerships.

RESULTS

As of August 2017, 1,044 (92.3% of eligible) patients with SCD have enrolled in the study (860 children and 184 adults), with 11,915 person-years of observation. Population demographics included mean age at last visit of 11.3 years (range 0.7-30.1), 49.8% females, 57.7% treated with hydroxyurea, 8.5% treated with monthly transfusions, and 62.9% hemoglobin (Hb) SS or HbSB⁰ -thalassemia, 25.7% HbSC, 8.4% HbsB⁺ -Thalassemia, 1.7% HbS/HPFH, and 1.2% other.

CONCLUSIONS

The SCCRIP cohort will provide a rich resource for the conduct of high impact multidisciplinary research in SCD.

White matter integrity and processing speed in sickle cell anemia

Objective

The purpose of this retrospective cross-sectional study was to investigate whether changes in white matter integrity are related to slower processing speed in sickle cell anemia.

Methods

Thirty-seven patients with silent cerebral infarction, 46 patients with normal MRI, and 32 sibling controls (age range 8–37 years) underwent cognitive assessment using the Wechsler scales and 3-tesla MRI. Tract-based spatial statistics analyses of diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI) parameters were performed.

Results

Processing speed index (PSI) was lower in patients than controls by 9.34 points (95% confidence interval: 4.635–14.855, p = 0.0003). Full Scale IQ was lower by 4.14 scaled points (95% confidence interval: −1.066 to 9.551, p = 0.1), but this difference was abolished when PSI was included as a covariate (p = 0.18). There were no differences in cognition between patients with and without silent cerebral infarction, and both groups had lower PSI than controls (both p < 0.001). In patients, arterial oxygen content, socioeconomic status, age, and male sex were identified as predictors of PSI, and correlations were found between PSI and DTI scalars (fractional anisotropy r = 0.614, p < 0.00001; r = −0.457, p < 0.00001; mean diffusivity r = −0.341, p = 0.0016; radial diffusivity r = −0.457, p < 0.00001) and NODDI parameters (intracellular volume fraction r = 0.364, p = 0.0007) in widespread regions.

Conclusion

Our results extend previous reports of impairment that is independent of presence of infarction and may worsen with age. We identify processing speed as a vulnerable domain, with deficits potentially mediating difficulties across other domains, and provide evidence that reduced processing speed is related to the integrity of normal-appearing white matter using microstructure parameters from DTI and NODDI.

Overnight auto-adjusting continuous airway pressure + standard care compared with standard care alone in the prevention of morbidity in sickle cell disease phase II (POMS2b): study protocol for a randomised controlled trial

Background

In addition to pain, sickle cell anaemia (HbSS) complications include neurocognitive difficulties in attention and processing speed associated with low daytime and night-time oxygen saturation compounded by obstructive sleep apnoea (OSA). In the general population OSA is treated with continuous positive airways pressure (CPAP). The aim of this single-blind, randomised, controlled phase II trial is to compare auto-adjusting CPAP (APAP) with standard care to standard care alone in individuals with HbSS to determine whether the intervention improves attention and processing speed, brain structure, pain and quality of life.

Methods/Design

Eligibility criteria include: ability to provide informed consent; age > 8 years; diagnosis of HbSS; and mean overnight saturation of < 90% for < 30% of the night (i.e. not meeting current criteria for overnight oxygen therapy). Key exclusion criteria are: overnight respiratory support; respiratory or decompensated cardiac failure; chronic transfusion; or contraindications to APAP therapy or magnetic resonance imaging (MRI).

Sixty individuals with HbSS (30 children and 30 adults) will be randomised to standard care + APAP or standard care alone for six months. Minimisation factors are: age group (8–11, 12–15, 16–22 and > 23 years); silent infarction on MRI; minimum overnight oxygen saturation > 90% or < 90%; and hydroxyurea use.

For APAP individuals, the intervention is administered at home. Adherence and effectiveness are recorded using software documenting hours of use each night and overnight oximetry. Participant support in terms of appropriate facemask and facilitating adherence are provided by an unblinded sleep physiologist.

The primary outcome is change in the cancellation subtest from the Wechsler scales. Secondary outcomes include general cognitive functioning, quantitative brain MRI, blood and urine chemistry, quality of life and daily pain via a smartphone App (GoMedSolutions, Inc) and, where possible MRI heart, echocardiography, and 6-min walk. These outcomes will be assessed at baseline and after six months of treatment by assessors blind to treatment assignment.

Discussion

Altering oxygen saturation in HbSS may lead to bone marrow suppression. This risk will be reduced by monitoring full blood counts at baseline, two weeks, three months and six months, providing treatment as appropriate and reporting as safety events.

Trial registration

ISRCTN46012373. Registered on 10 July 2015.

Protocol Version: 6.0 Date: 24th December 2015

Sponsor: University Hospital Southampton. Sponsor’s protocol code: RHMCHIOT53

Silent cerebral infarct definitions and full-scale IQ loss in children with sickle cell anemia

OBJECTIVE

To evaluate whether application of the adult definition of silent cerebral infarct (SCI) (T2-weighted hyperintensity ≥5 mm with corresponding T1-weighted hypointensity on MRI) is associated with full-scale IQ (FSIQ) loss in children with sickle cell anemia (SCA), and if so, whether this loss is greater than that of the reference pediatric definition of SCI (T2-weighted hyperintensity ≥3 mm in children on MRI; change in FSIQ -5.2 points; p = 0.017; 95% confidence interval [CI] -9.48 to -0.93).

METHODS

Among children with SCA screened for SCI in the Silent Cerebral Infarct Transfusion trial, ages 5-14 years, a total of 150 participants (107 with SCIs and 43 without SCIs) were administered the Wechsler Abbreviated Scale of Intelligence. A multivariable linear regression was used to model FSIQ in this population, with varying definitions of SCI independently substituted for the SCI covariate.

RESULTS

The adult definition of SCI applied to 27% of the pediatric participants with SCIs and was not associated with a statistically significant change in FSIQ (unstandardized coefficient -3.9 points; p = 0.114; 95% CI -8.75 to 0.95), with predicted mean FSIQ of 92.1 and 96.0, respectively, for those with and without the adult definition of SCI.

CONCLUSIONS

The adult definition of SCI may be too restrictive and was not associated with significant FSIQ decline in children with SCA. Based on these findings, we find no utility in applying the adult definition of SCI to children with SCA and recommend maintaining the current pediatric definition of SCI in this population.

The case for HLA-identical sibling hematopoietic stem cell transplantation in children with symptomatic sickle cell anemia

This article has a companion Counterpoint by DeBaun and Clayton.

Low fetal hemoglobin percentage is associated with silent brain lesions in adults with homozygous sickle cell disease

Silent white matter changes (WMCs) on brain imaging are common in individuals with sickle cell disease (SCD) and are associated with cognitive deficits in children. We investigated the factors predictive of WMCs in adults with homozygous SCD and no history of neurological conditions. Patients were recruited from a cohort of adults with homozygous SCD followed up at an adult sickle cell referral center for which steady-state measurements of biological parameters and magnetic resonance imaging scans of the brain were available. WMCs were rated by consensus, on a validated age-related WMC scale. The prevalence of WMCs was 49% (95% confidence interval [CI], 39%-60%) in the 83 patients without vasculopathy included. In univariable analysis, the patients who had WMCs were more likely to be older (P = .003) and to have hypertension (P = .02), a lower mean corpuscular volume (P = .005), a lower corpuscular hemoglobin concentration (P = .008), and a lower fetal hemoglobin percentage (%HbF) (P = .003). In multivariable analysis, only a lower %HbF remained associated with the presence of WMCs (odds ratio [OR] per 1% increase in %HbF, 0.84; 95% CI, 0.72-0.97; P = .021). %HbF was also associated with WMC burden (P for trend = .007). Multivariable ordinal logistic regression showed an inverse relationship between WMC burden (age-related WMC score divided into 4 strata) and HbF level (OR for 1% increase in %HbF, 0.89; 95% CI, 0.79-0.99; P = .039). Our study suggests that HbF may protect against silent WMCs, decreasing the likelihood of WMCs being present and their severity. It may therefore be beneficial to increase HbF levels in patients with WMCs.

Contrasting resting-state fMRI abnormalities from sickle and non-sickle anemia

Sickle cell disease (SCD) is a chronic blood disorder that is often associated with acute and chronic cerebrovascular complications, including strokes and impaired cognition. Using functional resting state magnetic resonance images, we performed whole-brain analysis of the amplitude of low frequency fluctuations (ALFF), to detect areas of spontaneous blood oxygenation level dependent signal across brain regions. We compared the ALFF of 20 SCD patients to that observed in 19 healthy, age and ethnicity-matched, control subjects. Significant differences were found in several brain regions, including the insula, precuneus, anterior cingulate cortex and medial superior frontal gyrus. To identify the ALFF differences resulting from anemia alone, we also compared the ALFF of SCD patients to that observed in 12 patients having comparable hemoglobin levels but lacking sickle hemoglobin. Increased ALFF in the orbitofrontal cortex and the anterior and posterior cingulate cortex and decreased ALFF in the frontal pole, cerebellum and medial superior frontal gyrus persisted after accounting for the effect of anemia. The presence of white matter hyperintensities was associated with depressed frontal and medial superior frontal gyri activity in the SCD subjects. Decreased ALFF in the frontal lobe was correlated with decreased verbal fluency and cognitive flexibility. These findings may lead to a better understanding of the pathophysiology of SCD.

Disease severity and slower psychomotor speed in adults with sickle cell disease

Psychomotor slowing is common in children with sickle cell disease (SCD), but little is known about its severity in adults. We conducted a cross-sectional study to quantify psychomotor speed, measured with the digit symbol substitution test (DSST), in relationship with disease severity in adults with SCD attending an outpatient clinic (n = 88, age 36.3 years). Genotype was used to group patients in "severe" (homozygous for hemoglobin S or compound heterozygous with β⁰ thalassemia) or "moderate" groups (compound heterozygous for HbS, with either HbC or β⁺ thalassemia). Analyses were repeated after exclusion of patients with a history of stroke (n = 11). Mild impairment in processing speed was detectable in both the "severe" and the "moderate" group (30% and 9%, respectively; age-adjusted P = .14). Compared with the "moderate" group, those in the "severe" group had significantly lower standardized DSST scores (P = .004), independent of adjustment for factors that differed between the groups: hemoglobin, ferritin, hydroxyurea use, blood pressure parameters, and stroke history. Results were similar after excluding patients with stroke. Psychomotor slowing in SCD differs in relationship to genotype; this difference appears unrelated to history of stroke or severity of anemia and other risk factors examined cross-sectionally. Although less prevalent, mild cognitive impairment was also detectable in patients with a less severe genotype. Longitudinal studies of SCD should include all diseases genotypes and examine factors that would reduce the risk of slow processing speed and perhaps more general cognitive impairment in each subgroup.

Graph Lasso-Based Test for Evaluating Functional Brain Connectivity in Sickle Cell Disease

Sickle cell disease (SCD) is a vascular disorder that is often associated with recurrent ischemia-reperfusion injury, anemia, vasculopathy, and strokes. These cerebral injuries are associated with neurological dysfunction, limiting the full developing potential of the patient. However, recent large studies of SCD have demonstrated that cognitive impairment occurs even in the absence of brain abnormalities on conventional magnetic resonance imaging (MRI). These observations support an emerging consensus that brain injury in SCD is diffuse and that conventional neuroimaging often underestimates the extent of injury. In this article, we postulated that alterations in the cerebral connectivity may constitute a sensitive biomarker of SCD severity. Using functional MRI, a connectivity study analyzing the SCD patients individually was performed. First, a robust learning scheme based on graphical lasso model and Fréchet mean was used for estimating a consistent descriptor of healthy brain connectivity. Then, we tested a statistical method that provides an individual index of similarity between this healthy connectivity model and each SCD patient's connectivity matrix. Our results demonstrated that the reference connectivity model was not appropriate to model connectivity for only 4 out of 27 patients. After controlling for the gender, two separate predictors of this individual similarity index were the anemia (p = 0.02) and white matter hyperintensities (WMH) (silent stroke) (p = 0.03), so that patients with low hemoglobin level or with WMH have the least similarity to the reference connectivity model. Further studies are required to determine whether the resting-state connectivity changes reflect pathological changes or compensatory responses to chronic anemia.

The effects of music therapy on transition outcomes in adolescents and young adults with sickle cell disease

Background The Build, Educate, Advance, Transition, in Sickle cell disease (BEATS) music therapy program was developed to address health challenges faced by adolescents/young adults (AYA) with sickle cell disease (SCD) during the transition to adult medical care. Objective The purpose of this study was to investigate the effects of BEATS on self-efficacy, trust, knowledge about SCD, and adherence in adolescents/young adults (AYA) with SCD. Subjects Thirty AYA with SCD, 18-23 years old, recruited from an adult SCD clinic agreed to participate in four BEATS sessions over 1 year. Methods Self-efficacy, trust and SCD knowledge were measured prospectively at baseline and months 3, 6, 9, and 12. Adherence to clinic appointments and healthcare utilization were measured retrospectively from medical records. A repeated measures linear mixed-effect model with compound symmetry covariance structure was used to fit the data. Results BEATS participants demonstrated a significant improvement in SCD knowledge (p = 0.0002) compared to baseline, an increase in acute care clinic, but not emergency department, utilization (p = 0.0056), and a non-significant improvement in clinic attendance (p = 0.1933). Participants' subjective evaluations revealed a positive response to BEATS. There were no significant changes in self-efficacy, trust, hospital admissions, or blood transfusion adherence. Conclusion Culturally tailored, developmentally appropriate music therapy transition interventions can concretely improve SCD knowledge and may improve transition for AYA with SCD.

Attention Deficit Hyperactivity Disorder in Children With Sickle Cell Disease Referred for an Evaluation

Neuropsychological deficits, including difficulties with attention, are well described in children with sickle cell disease (SCD). Very little is known about attention deficit hyperactivity disorder (ADHD) in children with SCD. The objective of this study was to determine the proportion of ADHD in children with SCD referred for neuropsychological evaluation. This prospective, cross-sectional study included patients (age, 4 to 18 y) with SCD and completion of a neuropsychological evaluation between December 2013 and March 2016. Patients were referred for neuropsychological evaluation because of concern regarding school performance, development, and/or behavior. The diagnosis of ADHD was made by a neuropsychologist on the basis of the diagnostic criteria in the Diagnostic Statistical Manual-Fourth or Fifth Editions. ADHD medication usage rate was obtained by medical record review. Of the 89 patients with SCD referred for neuropsychological evaluation, 25% (95% confidence interval, 16%-35%) met diagnostic criteria for ADHD. Only 21% of the patients with SCD and ADHD were prescribed an ADHD medication. Our study supports routine ADHD screening in children with SCD who have poor school performance or behavioral concerns. Despite the benefits of pharmacologic treatment, the majority of patients with SCD and ADHD did not receive a medication for management of their ADHD.

Differences in Activation and Deactivation in Children with Sickle Cell Disease Compared with Demographically Matched Controls

BACKGROUND AND PURPOSE

Declines in both functional activation and functional connectivity have been reported in patients with sickle cell disease. In this study, we derived the functional and default mode responses to a word stem paradigm in age-, ethnicity-, and background-matched subjects with sickle cell disease and control groups, with the aim of testing whether both networks were similarly attenuated and whether the changes were related to physiologic parameters that characterize sickle cell disease.

MATERIALS AND METHODS

Both the functional and default mode responses were obtained from age- and background-matched controls and the sickle cell population by using a visually presented word stem paradigm on a 3T scanner.

RESULTS

We observed an attenuated response to both activation and deactivation in the sickle cell disease group. There were no significant differences in the activation response between the 2 groups for the contrast control > sickle cell disease; however, significant differences were observed in the medial parietal cortex, the auditory cortex, and the angular gyrus for the default mode. For the sickle cell group, a significant correlation between the activation z scores and the physiologic parameters was observed; for the deactivation, the results were not significant but the trend was similar.

CONCLUSIONS

The results indicate that the physiologic parameters modulate the activation in the expected fashion, but that the effect was weaker for deactivation. Given that significant differences between the 2 groups were only seen for deactivation, additional factors must modulate the deactivation in sickle cell disease.