Neurodevelopmental deficits among infants and toddlers with sickle cell disease

Executive Function and Processing Speed in Children Living with Sickle Cell Anemia

Executive function and processing speed difficulties are observed in children living with sickle cell anemia (SCA). The influence of processing speed on executive function is not well understood. We recruited 59 children living with SCA and 24 matched controls aged 8-18 years between 2010 and 2016 from clinics in the UK. Children completed tests in processing speed and cognitive flexibility, subdomains of executive function. MRI scans were conducted within one year of testing; oxygen saturation was obtained on the day of testing. Hemoglobin levels were obtained from medical records. Caregivers completed the executive function questionnaire. Hierarchical linear regressions found that hemoglobin, oxygen saturation, age, infarct status, and processing speed were not independent predictors for any model. However, for all cognitive flexibility tests, there was a significant interaction between infarct status and processing speed; children without silent cerebral infarction (SCI) with faster processing speed had better cognitive flexibility. Our findings indicate that, when interpreting executive function difficulties, it is important to account for the relationship between SCI status and processing speed. More research is needed to elucidate the mechanisms, but clinically, including executive function testing as part of clinic visits by embedding psychologists within the healthcare team would appear to be a critical step.

The Development of Neuroimaging Biomarkers for Cognitive Decline in Sickle Cell Disease

Sickle cell disease (SCD) is complicated by neurologic complications including vasculopathy, hemorrhagic or ischemic overt stroke, silent cerebral infarcts and cognitive dysfunction. Patients with SCD, even in the absence of vasculopathy or stroke, have experience cognitive dysfunction that progresses with age. Transcranial Doppler ultrasound and structural brain MRI are currently used for primary and secondary stroke prevention, but laboratory or imaging biomarkers do not currently exist that are specific to the risk of cognitive dysfunction in patients with SCD. Recent investigations have used advanced MR sequences assessing cerebral hemodynamics, white matter microstructure and functional connectivity to better understand the pathophysiology of cognitive decline in SCD, with the long-term goal of developing neuroimaging biomarkers to be used in risk prediction algorithms and to assess the efficacy of treatment options for patients with SCD.

Sociodemographic and Biomedical Correlates of Developmental Delay in 2- and 4-Year-Olds with Sickle Cell Disease

BACKGROUND

Developmental delay occurs frequently in sickle cell disease (SCD). Psychosocial and biomedical factors contribute to delays, but most studies have not examined the timing of risk factors and developmental delay. We examined sociodemographic and biomedical factors to evaluate whether risks of developmental delay differed across 2 developmental periods.

METHODS

We examined Ages and Stages Questionnaire, second edition (ASQ-2), outcomes in 2-year-olds (n = 100) and 4-year-olds (n = 101) with SCD. ASQ-2 data were obtained from routine developmental screenings administered as part of health care between 2009 and 2016 at a single hematology clinic. Medical record reviews were used to identify sociodemographic and biomedical factors associated with positive screenings for developmental delay.

RESULTS

Two-year-olds with positive ASQ-2 screenings (n = 32; 32%) were less likely to have private health insurance or to have been in formal daycare and more likely to have a severe SCD genotype. Four-year-olds with positive screenings (n = 40; 40%) were more likely to have a severe SCD genotype or an abnormal transcranial Doppler ultrasound (TCD) examination indicating high stroke risk. The strength of the association between positive screenings and insurance status, severe genotypes, and TCD examinations differed across the 2 age groups. Domain-level outcomes on the ASQ-2 also differed across the 2 age groups.

CONCLUSION

The cross-sectional data indicate biomedical and psychosocial risks are related to developmental delay, but the association with specific risk factors differs across age.

Changes in the developmental status of preschoolers with sickle cell disease

Developmental monitoring and screening are recommended strategies for identifying children with sickle cell disease at high risk for cerebrovascular complications. Studies examining developmental screenings have provided little data on change over time. We examined screenings longitudinally in 43 children screened as two-year-olds and four-year-olds using the Ages and Stages Questionnaire, 2nd edition. Only two-thirds of children had stable screening outcomes. A new onset of cerebrovascular complications predicted the emergence of developmental delay (P = 0.017). Multivariate analysis suggested a benefit from formal developmental interventions. Regular developmental screening during the preschool period is important to identify systematic changes in developmental status.

Neurocognitive functioning in preschool children with sickle cell disease

BACKGROUND

Children with sickle cell disease (SCD) experience neurodevelopmental delays; however, there is limited research with preschool-age children. This study examined neurocognitive risk and protective factors in preschoolers with SCD.

PROCEDURE

Sixty-two patients with SCD (60% HbSS/HbSβ⁰ -thalassemia; 40% HbSC/HbSβ⁺ -thalassemia) between the ages of 3 and 6 years (mean = 4.77 years) received a neuropsychological evaluation as routine systematic surveillance. Patients were not selected for disease severity, prior central nervous system findings, or existing cognitive concerns. Thirty-four patients (82% HbSS/HbSβ⁰ -thalassemia) were prescribed hydroxyurea (HU) at the time of their neuropsychological evaluation. On average, these patients had been prescribed HU at 2.15 (standard deviation = 1.45) years of age. The average dose was 28.8 mg/kg/day. Besides genotype, there were no group differences in medical or demographic factors based on HU treatment status.

RESULTS

Patients with HbSS/HbSβ⁰ -thalassemia scored below normative expectations on measures of intelligence, verbal comprehension, and school readiness (false discovery rate-adjusted p-value [p_FDR ] < .05). Age, sickle genotype, and HU treatment exposure were not associated with measured neurocognitive outcomes (p_FDR  > .05). Greater social vulnerability at the community level was associated with poorer performance on measures of intellectual functioning, verbal comprehension, visuomotor control, and school readiness, as well as parent report of executive dysfunction (p_FDR  < .05). Greater household socioeconomic status was positively associated with academic readiness.

CONCLUSIONS

Preschoolers with severe SCD (HbSS/HbSβ⁰ -thalassemia) perform below age expectations on measures of intelligence and academic readiness. Sociodemographic factors were stronger drivers of neurocognitive performance than disease severity or disease-modifying treatment. Neurodevelopmental interventions targeting the home and broader community environment are needed.

Neurocognitive risk in sickle cell disease: Utilizing neuropsychology services to manage cognitive symptoms and functional limitations

Sickle cell disease (SCD) is an inherited blood disorder that is associated with developmental delays and neurocognitive deficits. This review details key findings related to neurocognitive outcomes for children and adults with emphasis on the impact of neurological correlates and disease severity. Associations between neurocognition, demographic factors and social determinants of health are also reviewed. Emerging literature has reported on the neurocognitive impact of SCD in children and adolescents in Africa and Europe, including children from immigrant communities. Neurocognitive deficits are linked to poor functional outcomes, including transition from paediatric to adult care, medication adherence and unemployment. Integrating neuropsychology into multidisciplinary care for individuals with SCD can assist with identification and management of neurocognitive concerns, intervention development, individualized care plan development and continued multidisciplinary research.

Developmental delay in infants and toddlers with sickle cell disease: a systematic review

AIM

To summarize developmental delay among infants and toddlers with sickle cell disease (SCD).

METHOD

This systematic review included studies that reported developmental outcomes of children with SCD between 0 months and 48 months of age and followed standards set forth by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

Ten studies were included, describing 596 unique developmental assessments. The rate of developmental delay ranged from 17.5% to 50% and increased with age. Cognition was the only domain included in all studies and the most frequently identified delay. One study reported that more severe SCD genotypes predicted worse development, while five studies reported no difference in rates of developmental delay across genotypes.

INTERPRETATION

These findings emphasize the need for standardized screening to identify children with SCD at risk of delay at a young age to facilitate appropriate referrals for therapeutic intervention. Frequent and comprehensive developmental screening is necessary among all SCD genotypes.

Physical Impairment and Function in Children and Adolescents With Sickle Cell Disease: A Systematic Review

OBJECTIVE

To examine physical impairments and physical function in children and adolescents with sickle cell disease (SCD).

DATA SOURCES

PubMed, Embase (embase.com), Cumulative Index to Nursing and Allied Health (EBSCO), Cochrane Central Register of Controlled Trials (Wiley), and Dissertations and Theses (ProQuest) were searched from January 1, 1990, to September 25, 2020. References retrieved were required to include a term for SCD and a term for physical impairments or physical function. Results were limited to articles with children and adolescents and in the English language.

STUDY SELECTION

A total of 3054 nonduplicate articles were independently screened by 2 reviewers, resulting in 240 articles for full-text review. The full-text review, performed by 2 independent reviewers, resulted in 67 articles.

DATA EXTRACTION

Data were extracted from each full text to a custom Excel document by a single reviewer and were verified by a secondary reviewer.

DATA SYNTHESIS

The studies identified in this systematic review offer evidence that children and adolescents with SCD demonstrate physical impairments and physical function limitations compared with control participants as noted by varying percentages in deficits up to 19%-58% in muscle and bone composition and/or symptoms, muscle strength, cardiopulmonary function, motor performance, physical activity, and physical function domains of quality of life questionnaires.

CONCLUSIONS

Children and adolescents with SCD present with physical impairments and physical function limitations. Scientists and clinicians should consider developing collaborative standards to define and objectively measure physical impairment and function in this population to comprehensively examine the underlying factors that contribute to physical impairments and function.

Epidemiology of Stroke in Sickle Cell Disease

Sickle cell disease is the most common cause of stroke in childhood, both ischaemic and haemorrhagic, and it also affects adults with the condition. Without any screening or preventative treatment, the incidence appears to fall within the range 0.5 to 0.9 per 100 patient years of observation. Newborn screening with Penicillin prophylaxis and vaccination leading to reduced bacterial infection may have reduced the incidence, alongside increasing hydroxyurea prescription. Transcranial Doppler screening and prophylactic chronic transfusion for at least an initial year has reduced the incidence of stroke by up to 10-fold in children with time averaged mean of the maximum velocity >200 cm/s. Hydroxyurea also appears to reduce the incidence of first stroke to a similar extent in the same group but the optimal dose remains controversial. The prevention of haemorrhagic stroke at all ages and ischaemic stroke in adults has not yet received the same degree of attention. Although there are fewer studies, silent cerebral infarction on magnetic resonance imaging (MRI), and other neurological conditions, including headache, epilepsy and cognitive dysfunction, are also more prevalent in sickle cell disease compared with age matched controls. Clinical, neuropsychological and quantitative MRI screening may prove useful for understanding epidemiology and aetiology.

Pediatric Neurodevelopmental Delays in Children 0 to 5 Years of Age With Sickle Cell Disease: A Systematic Literature Review

INTRODUCTION

Sickle cell disease (SCD) is the most common abnormal genetic blood disease that affects ∼100,000 Americans. Approximately 20% to 37% of children with sickle cell anemia have silent cerebral infarcts by the age of 14 years old. Neurocognitive deficits are identified in infants and preschool children with SCD. The purpose of this systematic literature review is to provide a comprehensive understanding of the prevalence, severity, and the associated risk factors for neurodevelopmental delays (NDDs) in children with SCD 5 years of age and younger.

METHODS

Systematic search of 6 databases identified 2467 potentially relevant publications and 8 were identified through a manual search. Only 24 articles met the inclusion criteria.

RESULTS

We identified an increased prevalence of NDDs (cognitive, motor, or both). Children experienced deficits with language, attention and behavior, executive functioning, school readiness and/or academic performance, and motor skills (fine and gross motor functioning). Risk factors include silent cerebral infarcts and strokes, SCD genotype (HbSS>HbSC), other biologic, and social factors.

CONCLUSION

NDDs are common in children ages 0 to 5 years old with SCD. There is an opportunity to improve adherence to national guideline recommendations and early detection practices by pediatricians, hematologists, and other health care providers.

Activity competence among infants and toddlers with developmental disabilities: Rasch analysis of the Infant Toddler Activity Card Sort (ITACS)

Background

Development is rapid in the first years of life. Developmental delays appearing during this critical period have the potential to persist throughout the child’s life. Available standardized assessments for this age record a child’s ability to successfully complete discrete skills but fail to capture whether the child incorporates those skills into daily routines that are meaningful to the child and family. The Infant Toddler Activity Card Sort (ITACS) is a newly developed photograph-based early intervention tool to measure the participation-related concept of activity competence using caregiver report. The purpose of the present study was to use Rasch analysis to determine if ITACS items comprehensively measure the construct of child activity competence.

Results

A total of 60 child/caregiver dyads participated. The dichotomous caregiver-reported responses (present vs. absent) on the 40 individual ITACS items were used in Rasch analysis, and three iterations of the model were completed. The final model included 51 child/caregiver dyads and 67 ITACS assessments with a good spread of individual ability measure (6.47 logits). All items demonstrated adequate infit except for “sleeping” (range 0.68–1.54). Five items (sleeping, eating at restaurants, brushing teeth, crawling, and interact with pets) demonstrated high Mean Square (MNSQ) outfit statistics and one (take a bath) demonstrated low MNSQ outfit. ITACS items demonstrated a good spread of item difficulty measures (6.27 logits), and a clear ceiling was observed. Three activity items (smiling, breastfeeding, and playing with adults) were rarely endorsed as concerns. The activities most likely to be reported as challenging were “crying/communicating” and “going to school”. Person and item reliability statistics were adequate (0.79 and 0.80, respectively). The separation between individuals and between items were adequate to good (1.96 and 1.99, respectively).

Conclusions

Findings indicate that ITACS items are measuring a unidimensional construct--activity competence in early childhood. The Rasch analysis of caregiver responses suggest that some activities are more likely to be considered challenging and may be important targets for intervention. These results provide evidence to further validate the ITACS as a caregiver report measure and support its use in the early intervention setting to facilitate caregiver driven goal development.

Executive function in children with sickle cell anemia on transfusion: NIH toolbox utility in the clinical context

OBJECTIVE

The aim of this study was to establish the utility of the NIH Toolbox as a cognitive screener of executive functions in the clinical context. Additionally, we aimed to investigate whether age and time on transfusion were related to executive function performance. Method: Twenty-eight children and adolescents with sickle cell anemia (SCA) between 8 and 18 years (M = 13.28, SD = 3.05) on transfusion treatment were included. Participants completed five NIH Toolbox tasks (three executive function tasks and two non-executive function control tasks). Results: Mean scores on one of the three executive function measures (inhibitory control) fell below the average range (M = 81.36, SD = 14.01) with approximately 70% of children from both groups below the average range. Scores for processing speed (M = 86.82, SD = 22.01) and cognitive flexibility (M = 85.75, SD = 12.67) were low averages. As expected, scores on non-executive measures (language and memory) fell within the average range. No significant differences were observed between children with silent stroke and no stroke on executive function measures. Older age (p < .01) and length of time on transfusion (p < .05) predicted lower inhibitory control scores. Conclusions: Findings provide evidence for poor development of inhibitory control with age in this patient population. As the NIH Toolbox successfully highlighted expected deficits in this patient population, this study supports the use of this tool as a brief screening measure for children with SCD. The clinical and theoretical implications of the findings are discussed.

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.

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.

Associations of transcranial doppler velocity, age, and gender with cognitive function in children with sickle cell anemia in Nigeria

Children with sickle cell anemia (SCA) have elevated cerebral blood velocity relative to healthy peers. The primary aim of this study was to evaluate the association between cerebral blood velocity, measured by transcranial Doppler (TCD) ultrasound, age, and gender with cognitive function in children with SCA in Nigeria. Eighty-three children (Mage = 9.10, SD = 1.90 years; 55% female) with SCA in Nigeria completed cognitive assessments and a TCD ultrasound. The association between TCD velocity and measures of perceptual reasoning (Raven's Progressive Matrices), working memory (WISC-IV Digit Span), and executive planning (Tower of London, TOL) were assessed. Results showed that elevated TCD velocity significantly predicted lower scores on TOL Time Violations and Total Problem-Solving Time when controlling for BMI, hemoglobin level, and parent education, suggesting that TCD velocity is related to the efficiency of executive function. Further, age was negatively related to children's performance on the Ravens Matrices and TOL Total Correct, and boys showed greater deficits on the TOL Total Correct relative to girls. Moderation analyses for gender showed that there was a conditional negative association between TCD velocity and Digit Span for boys, but not for girls. Findings suggest that children with SCA in Nigeria with elevated TCD velocity are at risk for deficits in efficiency of executive planning, and boys with elevated TCD velocity are particularly at increased risk for deficits in auditory working memory. Implications of this study are important for interventions to reduce cerebral blood velocity and the use of TCD in this population.

Assessment of Executive Functions in Preschool Children With Sickle Cell Anemia

OBJECTIVES

Children with sickle cell anemia (SCA) are commonly reported to experience executive dysfunction. However, the development of executive function (EF) in preschool-age children without stroke in this patient population has not been investigated so it is unclear when and how these deficits emerge.

METHODS

This case-control study examines the feasibility of assessing the early development of executive functioning in 22 preschool children years with SCA in the domains of processing speed, working memory, attention, inhibitory control, and cognitive flexibility, as well as everyday function, in comparison to matched control children.

RESULTS

A pattern of potential deficits in early emerging executive skills was observed in the domains of inhibitory control and cognitive flexibility. Parents reported no differences for everyday EF and no significant differences were observed for working memory and processing speed.

CONCLUSIONS

Results suggest that deficits in everyday executive difficulties, working memory, and processing speed, as commonly reported for older children with SCA, may not yet have emerged at this early developmental stage, despite specific deficits in cognitive flexibility and inhibitory control on behavioral measures. The feasibility of using available executive measures with preschool age children to characterize the development of early EF skills is discussed. (JINS, 2018, 24, 949-954).

Sickle Cell Disease: Bone, Joint, Muscle, and Motor Complications

Sickle cell disease (SCD) is a group of inherited disorders caused by a mutation of the hemoglobin gene, resulting in the formation of abnormal, sickle-shaped red blood cells. It is a lifelong condition characterized by anemia, vaso-occlusion, and decreased blood flow to vital tissues. Sickle cell disease affects every major organ and significantly reduces life expectancy of the affected individuals. Patients with SCD are at an increased risk for developing musculoskeletal complications that decrease quality of life and contribute to the significant burden of the disease. Understanding these complications, as well as the genetics, pathophysiology, and epidemiology of SCD, will assist orthopaedic nurses in providing evidence-informed care.

Executive performance on the preschool executive task assessment in children with sickle cell anemia and matched controls

Executive deficits are commonly reported in children with sickle cell anemia. Earlier identification of executive deficits would give more scope for intervention, but this cognitive domain has not been routinely investigated due to a lack of age-appropriate tasks normed for preschool children. In particular, information relating to patient performance on an executive task that reflects an everyday activity in the classroom could provide important insight and practical recommendations for the classroom teacher at this key developmental juncture as they enter the academic domain. The performance of 22 children with sickle cell anemia was compared to 24 matched control children on the Preschool Executive Task Assessment. Findings reveal that children with sickle cell anemia are performing poorer than their matched peers on this multi-step assessment. In particular, children with sickle cell anemia required more structured support to shift focus after a completed step, as reflected by poorer scores in the quantitative Sequencing and Completion domains. They also required more support to stay on task, as seen by poorer ratings in the qualitative Distractibility domain. Abbreviations:PETA: Preschool Executive Task Assessment; SCA: Sickle Cell Anemia; EF: Executive Functioning.

Predictive validity of developmental screening in young children with sickle cell disease: a longitudinal follow-up study

AIM

To assess the predictive validity of developmental screenings in children with sickle cell disease (SCD) for academic outcomes and stroke risk.

METHOD

Parent questionnaires and medical record data were collected for a cohort receiving developmental screenings between September 2004 and May 2008 as toddlers or early school age. Screening outcomes were dichotomized (positive, negative) by a priori criteria. Questionnaires assessed school and social functioning, services received, and quality of life. Medical record data assessed general SCD morbidity and stroke risk.

RESULTS

Forty-one toddlers (mean age 2y 5mo; 25 males, 16 females) and 49 early school-age children (mean age 6y 5mo; 26 males, 23 females) completed follow-up. The mean follow-up period was 8 years 6 months (range 6.1-10.8y). For toddlers, positive screenings for language delays predicted lower academic performance (p=0.023). For older children, positive screenings for cognitive delays predicted more frequent academic/attentional problems at school (p<0.001), grade retention (p=0.007), and lower academic performance (p=0.001). Positive screenings were associated with an earlier onset of school problems and lower quality of life. Positive screenings for language/cognitive delays predicted increased stroke risk (both p<0.05).

INTERPRETATION

Screening for language or cognitive development in young children with SCD predicts academic outcomes and stroke risk.

WHAT THIS PAPER ADDS

Developmental screening predicts academic outcomes in sickle cell disease. Children with concerning language/cognitive screenings have early-onset school difficulties. Developmental screenings may help predict cerebrovascular complications.

Developmental Screening in Pediatric Sickle Cell Disease: Disease-Related Risk and Screening Outcomes in 4 Year Olds

OBJECTIVE

Studies of early child development in sickle cell disease (SCD) have found modest associations between disease-related risks and developmental status in infants and toddlers, but such associations are evident by early elementary school. We screened 4-year-old children with SCD using 2 screening strategies to assess if biomedical risk factors for neurologic disease are related to developmental screening outcomes at this intermediate age.

METHODS

Seventy-seven 4-year-old children with SCD (M = 4.5 yrs, SD = 0.3 yrs) completed developmental screenings at routine hematology visits using child testing (Fluharty Preschool Speech and Language Screenings Test, 2nd edition) and parent-report (Ages and Stages Questionnaire, 2nd edition) procedures. Genotype and other biomedical variables were coded from medical records.

RESULTS

Children with higher-risk SCD genotypes (n = 52) showed lower performance than children with lower-risk genotypes (n = 25) on a measure related to neurologic disease risk in older children (syntactic processing); genotype risk was also related to rates of positive screenings on parent-reported developmental milestones (52% positive screenings in high-risk genotypes vs 12% in low-risk genotypes). Screening outcomes were also related to transcranial Doppler ultrasound findings assessing cerebral blood flow.

CONCLUSION

Developmental screening at age 4 may be a useful target age for identifying preschoolers with sickle cell-related neurodevelopmental concerns. Parent report of developmental milestones and behavioral testing each may have a role in screening for children in need of follow-up services to address potential neurodevelopmental effects from SCD.

Cognitive Functions and Psychological Problems in Children with Sickle Cell Anemia

OBJECTIVE

To study the cognitive functions and psychological problems in children with Sickle cell anemia (SCA).

METHODS

Children with SCA were compared with an age, sex- and community- matched control group of children with no SCA. Malins Intelligence Scale for Indian children, modified PGI memory scale, and Childhood Psychopathology Measurement Schedule were used to assess cognitive functions and psychological problems.

RESULTS

Verbal quotient, performance quotient and intelligence quotient in SCA group were 77, 81, 78, respectively versus 92, 95, 93, respectively in non-SCA group (P <0.001). Borderline intellectual functioning and mild mental retardation were more common in SCA (70< and 16<, respectively). Children with SCA had impaired attention, concentration and working memory and more behavior problems compared to children without SCA.

CONCLUSION

Cognitive functions are impaired in children with SCA and they have more psychological problems. Facilities for early identification and remediation of psychological and intellectual problems should be incorporated with health care services for children with sickle cell anemia.

Cognitive and behavior deficits in sickle cell mice are associated with profound neuropathologic changes in hippocampus and cerebellum

Strokes are perhaps the most serious complications of sickle cell disease (SCD) and by the fifth decade occur in approximately 25% of patients. While most patients do not develop strokes, mounting evidence indicates that even without brain abnormalities on imaging studies, SCD patients can present profound neurocognitive dysfunction. We sought to evaluate the neurocognitive behavior profile of humanized SCD mice (Townes, BERK) and to identify hematologic and neuropathologic abnormalities associated with the behavioral alterations observed in these mice. Heterozygous and homozygous Townes mice displayed severe cognitive deficits shown by significant delays in spatial learning compared to controls. Homozygous Townes also had increased depression- and anxiety-like behaviors as well as reduced performance on voluntary wheel running compared to controls. Behavior deficits observed in Townes were also seen in BERKs. Interestingly, most deficits in homozygotes were observed in older mice and were associated with worsening anemia. Further, neuropathologic abnormalities including the presence of large bands of dark/pyknotic (shrunken) neurons in CA1 and CA3 fields of hippocampus and evidence of neuronal dropout in cerebellum were present in homozygotes but not control Townes. These observations suggest that cognitive and behavioral deficits in SCD mice mirror those described in SCD patients and that aging, anemia, and profound neuropathologic changes in hippocampus and cerebellum are possible biologic correlates of those deficits. These findings support using SCD mice for studies of cognitive deficits in SCD and point to vulnerable brain areas with susceptibility to neuronal injury in SCD and to mechanisms that potentially underlie those deficits.

Determinants of cognitive outcomes of perinatal and childhood stroke: A review

Our understanding of cognitive and behavioral outcomes of perinatal and childhood stroke is rapidly evolving. A current understanding of cognitive outcomes following pediatric stroke can inform prognosis and direct interventions and our understanding of plasticity in the developing brain. However, our understanding of these outcomes has been hampered by the notable heterogeneity that exists amongst the pediatric stroke population, as the influences of various demographic, cognitive, neurological, etiological, and psychosocial variables preclude broad generalizations about outcomes in any one cognitive domain. We therefore aimed to conduct a detailed overview of the published literature regarding the effects of age at stroke, time since stroke, sex, etiology, lesion characteristics (i.e., location, laterality, volume), neurologic impairment, and seizures on cognitive outcomes following pediatric stroke. A key theme arising from this review is the importance of interactive effects among variables on cognitive outcomes following pediatric stroke. Interactions particularly of note include the following: (a) age at Stroke x Lesion Location; (b) Lesion Characteristics (i.e., volume, location) x Neurologic Impairment; (c) Lesion Volume x Time Since Stroke; (d) Sex x Lesion Laterality; and (e) Seizures x Time Since Stroke. Further, it appears that these relationships do not always apply uniformly across cognitive domains but, rather, are contingent upon the cognitive ability in question. Implications for future research directions are discussed.

Sickle cell disease in mice is associated with sensitization of sensory nerve fibers

The pain phenotype in sickle cell disease (SCD) patients is highly variable. A small percentage of SCD patients experience many vaso-occlusive crises/year, 5% of patients account for over 30% of pain episodes, while 39% report few episodes of severe pain. Clearly, a better understanding of the pathobiology of SCD is needed to improve its therapy. Humanized sickle cell mice recapitulate several phenotypes of SCD patients and provide a model for the study of SCD pain. Researchers have shown that one strain of humanized SCD mice, the BERK strain, has abnormal pain phenotype. However, the nociception phenotype of another humanized SCD mouse strain, the Townes strain, has not been described. In a large cross-sectional study of BERK and Townes SCD mice, we examined thermosensory response and sensory nerve fiber function using sine-wave electrical stimulation at 2000, 250, and 5 Hz to stimulate preferentially Aβ, Aδ, and C sensory nerve fibers, respectively. We found that BERK and Townes mice, compared to respective controls, had decreases in 2000, 250, and 5 Hz current vocalization thresholds in patterns that suggest sensitization of a broad spectrum of sensory nerve fibers. In addition, the pattern of sensitization of sensory fibers varied according to strain, sex, age, and mouse genotype. In a similarly variable pattern, Townes and BERKs also had significantly altered sensitivity to noxious thermal stimuli in agreement with what has been shown by others. In summary, the analysis of somatosensory function using sine-wave electrical stimulation in humanized sickle cell mice suggests that in SCD, both myelinated and unmyelinated, fibers are sensitized. The pattern of sensory fiber sensitization is distinct from that observed in pain models of neuropathic and inflammatory pain. These findings raise the possibility that sensitization of a broad spectrum of sensory fibers might contribute to the altered and variable nociception phenotype in SCD.