Statistical Approaches to Assess the Effects of Disease on Neurocognitive Function Over Time

Apolipoprotein-E4: risk of severe malaria and mortality and cognitive impairment in pediatric cerebral malaria

BACKGROUND

The relationship of apolipoprotein-E4 (APOE4) to mortality and cognition after severe malaria in children is unknown.

METHODS

APOE genotyping was performed in children with cerebral malaria (CM, n = 261), severe malarial anemia (SMA, n = 224) and community children (CC, n = 213). Cognition was assessed over 2-year follow-up.

RESULTS

A greater proportion of children with CM or SMA than CC had APOE4 (n = 162, 31.0%; n = 142, 31.7%; n = 103, 24.2%, respectively, p = 0.02), but no difference was seen in APOE3 (n = 310, 59.4%; n = 267, 59.6%; n = 282, 66.2%, respectively, p = 0.06), or APOE2 (n = 50, 9.6%; n = 39, 8.7%; and n = 41, 9.6%, respectively, p = 0.87). APOE4 was associated with increased mortality in CM (odds ratio, 2.28; 95% CI, 1.01, 5.11). However, APOE4 was associated with better long-term cognition (ß, 0.55; 95% CI, 0.04, 1.07, p = 0.04) and attention (ß 0.78; 95% CI, 0.26, 1.30, p = 0.004) in children with CM < 5 years old, but worse attention (ß, -0.90; 95% CI, -1.69, -0.10, p = 0.03) in children with CM ≥ 5 years old. Among children with CM, risk of post-discharge malaria was increased with APOE4 and decreased with APOE3.

CONCLUSIONS

APOE4 is associated with higher risk of CM or SMA and mortality in children with CM, but better long-term cognition in CM survivors <5 years of age.

Hydroxyurea Therapy for Neurological and Cognitive Protection in Pediatric Sickle Cell Anemia in Uganda (BRAIN SAFE II): Protocol for a single-arm open label trial

Background

Children with sickle cell anemia (SCA) in Sub-Saharan Africa are at high risk of sickle cerebrovascular injury (SCVI). Hydroxyurea, a commonly used disease-modifying therapy, may prevent or decrease SCVI for reduced incident stroke, stroke risk and potentially cognitive dysfunction. We aim to test the impact of daily hydroxyurea therapy on these outcomes in Ugandan children with SCA. We hypothesize that hydroxyurea therapy over 36 months will prevent, stabilize or improve these complications of SCA.

Methods

The BRAIN SAFE II study is an open-label, single-arm trial of daily hydroxyurea for 270 children with SCA (HbSS) in Uganda, ages 3-9 years. Following baseline assessments, participants began hydroxyurea therapy and clinically followed per local guidelines. Standard hydroxyurea dose is escalated to maximum tolerated dose (MTD). SCVI is assessed by cerebral arterial velocity using Doppler ultrasound, with cognitive function determined by formal neurocognitive testing (primary outcomes). Structural SCVI is assessed by magnetic resonance imaging (MRI) and angiography (MRA) in a sub-sample of 90 participants ages ≥5 years, along with biomarkers of anemia, inflammation and malnutrition (secondary outcomes). At trial midpoint (18 months) and completion (36 months), primary outcomes will be compared to participants' baseline to determine hydroxyurea impact and relationships to secondary outcomes.

Conclusion

This open-label, single-arm trial will examine the impact of hydroxyurea on preventing or ameliorating SCA SCVI in children, assessed by reducing incident stroke, stroke risk and neurocognitive dysfunction. Trial results will provide important insight into the role of hydroxyurea therapy on critical manifestations of SCVI in children with SCA.

Blood biomarkers of neuronal injury in paediatric cerebral malaria and severe malarial anaemia

Persistent neurodisability is a known complication in paediatric survivors of cerebral malaria and severe malarial anaemia. Tau, ubiquitin C-terminal hydrolase-L1, neurofilament-light chain, and glial fibrillary acidic protein have proven utility as biomarkers that predict adverse neurologic outcomes in adult and paediatric disorders. In paediatric severe malaria, elevated tau is associated with mortality and neurocognitive complications. We aimed to investigate whether a multi-analyte panel including ubiquitin C-terminal hydrolase-L1, neurofilament-light chain, and glial fibrillary acidic protein can serve as biomarkers of brain injury associated with mortality and neurodisability in cerebral malaria and severe malarial anaemia. In a prospective cohort study of Ugandan children, 18 months to 12 years of age with cerebral malaria (n = 182), severe malarial anaemia (n = 158), and asymptomatic community children (n = 118), we measured admission blood levels of ubiquitin C-terminal hydrolase-L1, neurofilament-light chain, and glial fibrillary acidic protein. We investigated differences in biomarker levels, associations with mortality, blood-brain barrier integrity, neurodeficits and cognitive Z-scores in survivors up to 24-month follow-up. Admission ubiquitin C-terminal hydrolase-L1 levels were elevated >95th percentile of community children in 71 and 51%, and neurofilament-light chain levels were elevated >95th percentile of community children in 40 and 37% of children with cerebral malaria and severe malarial anaemia, respectively. Glial fibrillary acidic protein was not elevated in disease groups compared with controls. In cerebral malaria, elevated neurofilament-light chain was observed in 16 children who died in hospital compared with 166 survivors (P = 0.01); elevations in ubiquitin C-terminal hydrolase-L1 levels were associated with degree of blood-brain barrier disruption (P = 0.01); and the % predictive value for neurodeficits over follow-up (discharge, 6-, 12-, and 24 months) increased for ubiquitin C-terminal hydrolase-L1 (60, 67, 72, and 83), but not neurofilament-light chain (65, 68, 60, and 67). In cerebral malaria, elevated ubiquitin C-terminal hydrolase-L1 was associated with worse memory scores in children <5 years at malaria episode who crossed to over 5 years old during follow-up cognitive testing [β -1.13 (95% confidence interval -2.05, -0.21), P = 0.02], and elevated neurofilament-light chain was associated with worse attention in children ≥5 years at malaria episode and cognitive testing [β -1.08 (95% confidence interval -2.05, -1.05), P = 0.03]. In severe malarial anaemia, elevated ubiquitin C-terminal hydrolase-L1 was associated with worse attention in children <5 years at malaria episode and cognitive testing [β -0.42 (95% confidence interval -0.76, -0.07), P = 0.02]. Ubiquitin C-terminal hydrolase-L1 and neurofilament-light chain levels are elevated in paediatric cerebral malaria and severe malarial anaemia. In cerebral malaria, elevated neurofilament-light chain is associated with mortality whereas elevated ubiquitin C-terminal hydrolase-L1 is associated with blood-brain barrier dysfunction and neurodeficits over follow-up. In cerebral malaria, both markers are associated with worse cognition, while in severe malarial anaemia, only ubiquitin C-terminal hydrolase-L1 is associated with worse cognition.

Admission Clinical and EEG Features Associated With Mortality and Long-term Neurologic and Cognitive Outcomes in Pediatric Cerebral Malaria

BACKGROUND AND OBJECTIVES

For children with cerebral malaria, mortality is high, and in survivors, long-term neurologic and cognitive dysfunctions are common. While specific clinical factors are associated with death or long-term neurocognitive morbidity in cerebral malaria, the association of EEG features with these outcomes, particularly neurocognitive outcomes, is less well characterized.

METHODS

In this prospective cohort study of 149 children age 6 months to 12 years who survived cerebral malaria in Kampala, Uganda, we evaluated whether depth of coma, number of clinical seizures, or EEG features during hospitalization were associated with mortality during hospitalization, short-term and long-term neurologic deficits, or long-term cognitive outcomes (overall cognition, attention, memory) over the 2-year follow-up.

RESULTS

Higher Blantyre or Glasgow Coma Scores (BCS and GCS, respectively), higher background voltage, and presence of normal reactivity on EEG were each associated with lower mortality. Among clinical and EEG features, the presence of >4 seizures on admission had the best combination of negative and positive predictive values for neurologic deficits in follow-up. In multivariable modeling of cognitive outcomes, the number of seizures and specific EEG features showed independent association with better outcomes. In children younger than 5 years throughout the study, seizure number and presence of vertex sharp waves were independently associated with better posthospitalization cognitive performance, faster dominant frequency with better attention, and higher average background voltage and faster dominant background frequency with better associative memory. In children younger than 5 years at CM episode but 5 years or older at cognitive testing, seizure number, background dominant frequency, and the presence of vertex sharp waves were each associated with changes in cognition, seizure number and variability with attention, and seizure number with working memory.

DISCUSSION

In children with cerebral malaria, seizure number is strongly associated with the risk of long-term neurologic deficits, while seizure number and specific EEG features (average background voltage, dominant rhythm frequency, presence of vertex sharp waves, presence of variability) are independently associated with cognitive outcomes. Future studies should evaluate the predictive value of these findings.

Association of Plasma Tau With Mortality and Long-term Neurocognitive Impairment in Survivors of Pediatric Cerebral Malaria and Severe Malarial Anemia

IMPORTANCE

Cerebral malaria (CM) and severe malarial anemia (SMA) are associated with persistent neurocognitive impairment (NCI) among children in Africa. Identifying blood biomarkers of acute brain injury that are associated with future NCI could allow early interventions to prevent or reduce NCI in survivors of severe malaria.

OBJECTIVE

To investigate whether acutely elevated tau levels are associated with future NCI in children after CM or SMA.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study was conducted at Mulago National Referral Hospital in Kampala, Uganda, from March 2008 to October 2015. Children aged 1.5 to 12 years with CM (n = 182) or SMA (n = 162) as well as community children (CC; n = 123) were enrolled in the study. Data analysis was conducted from January 2020 to May 2021.

EXPOSURE

CM or SMA.

MAIN OUTCOMES AND MEASURES

Enrollment plasma tau levels were measured using single-molecule array detection technology. Overall cognition (primary) and attention and memory (secondary) z scores were measured at 1 week and 6, 12, and 24 months after discharge using tools validated in Ugandan children younger than 5 years or 5 years and older.

RESULTS

A total of 467 children were enrolled. In the CM group, 75 (41%) were girls, and the mean (SD) age was 4.02 (1.92) years. In the SMA group, 59 (36%) were girls, and the mean (SD) age was 3.45 (1.60) years. In the CC group, 65 (53%) were girls, and the mean (SD) age was 3.94 (1.92) years. Elevated plasma tau levels (>95th percentile in CC group; >6.43 pg/mL) were observed in 100 children (55%) with CM and 69 children (43%) with SMA (P < .001). In children with CM who were younger than 5 years, elevated plasma tau levels were associated with increased mortality (odds ratio [OR], 3.06; 95% CI, 1.01-9.26; P = .048). In children with CM who were younger than 5 years at both CM episode and follow-up neurocognitive testing, plasma tau levels (log10 transformed) were associated with worse overall cognition scores over 24-month follow-up (β = -0.80; 95% CI, -1.32 to -0.27; P = .003). In children with CM who were younger than 5 years at CM episode and 5 years or older at follow-up neurocognitive testing, plasma tau was associated with worse scores in attention (β = -1.08; 95% CI, -1.79 to -0.38; P = .003) and working memory (β = -1.39; 95% CI, -2.18 to -0.60; P = .001).

CONCLUSIONS AND RELEVANCE

In this study, plasma tau, a marker of injury to neuronal axons, was elevated in children with CM or SMA and was associated with mortality and persistent NCI in children with CM younger than 5 years.

Attention Test Improvements from a Cluster Randomized Controlled Trial of Caregiver Training for HIV-Exposed/Uninfected Ugandan Preschool Children

OBJECTIVE

To report vigilance attention outcomes from a cluster randomized controlled trial of early childhood development caregiver training for perinatally HIV-exposed/uninfected preschool-age children in rural Uganda. The Early Childhood Vigilance Test (ECVT) provides a webcam recording of proportion of time a child views an animation periodically moving across a computer screen.

STUDY DESIGN

Sixty mothers/caregivers received biweekly year-long training sessions of the Mediational Intervention for Sensitizing Caregivers (MISC), and 59 mothers received biweekly training about nutrition, hygiene, and health care. Children were tested for attention at baseline, 6 months, and 12 months with the ECVT, in terms of proportion of time spent viewing a 6-minute animation of animals greeting the child and moving across the computer monitor screen. Time viewing the animation were scored by trained observers using ProCoder program for webcam scoring of proportion of time the child faced the animation. Mixed-effects modeling was used to compare ECVT outcomes for the 2 intervention groups.

RESULTS

Unadjusted and adjusted (for age, sex, height, and ECVT at baseline) group differences on ECVT significantly favored the MISC arm at 6 months (P = .03; 95% CI (0.01, 0.11), effect size = 0.46) but not at 12 months. Both groups made significant gains in sustained attention across the year-long intervention (P = .021) with no significant interaction effects between time and treatment arms or sex.

CONCLUSIONS

Caregiver early childhood development training enhanced attention in at-risk Ugandan children, which can be foundational to improved working memory and learning, and perhaps related to previous language benefits reported for this cohort.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT00889395.

Trajectories of cognitive function in community-dwelling older adults: A longitudinal study of population heterogeneity

INTRODUCTION

This study aimed to investigate cognitive aging trajectories, the associated sociodemographic characteristics, and the association of these trajectories with dementia.

METHODS

Generally healthy older adults (n = 19,114) were followed for up to 7 years, with regular cognitive assessments. Group-based trajectory modeling identified distinct cognitive trajectories.

RESULTS

Four to seven trajectories were identified per cognitive domain. Stable trajectories were observed across domains. Improvement in verbal fluency and minor psychomotor slowing were common. Substantial decline in global cognition and episodic memory were observed in a small proportion of individuals. Older, less educated participants and men were more common in lower-functioning trajectories (p < .001). The highest proportions of dementia cases were in trajectories with major decline in global cognition (56.9%) and memory (33.2%).

DISCUSSION

Inter-individual variability in cognitive trajectories was observed across all domains. Some individuals appear resilient to cognitive decline even with advancing age. Further research into factors promoting cognitive resilience is needed.

[Formula: see text]Neurodevelopmental assessment at one year of age predicts neuropsychological performance at six years in a cohort of West African Children

Rural children from Benin, west Africa were evaluated with the Mullen Scales of Early Learning (MSEL) at one year of age and then at six years with the Kaufman Assessment Battery for Children (KABC-II), the visual computerized Tests of Variables of Attention (TOVA), and the Bruininks-Oseretsky Test (BOT-2) of motor proficiency (N = 568). Although both the MSEL and KABC-II were available to the assessors in French, instructions to the mother/child were in local language of Fon. Mothers were evaluated with the Edinburgh Postpartum Depression Scale (EPDS), Caldwell HOME Scale, educational level and literacy, and a Socio-Economic Scale - also in their local language (Fon). After adjusting for maternal factors, MSEL cognitive composite was correlated with KABC-II with moderate effect sizes, but not with TOVA scores. Overall eta-squared effect for the multivariate models were moderately to strongly correlated (.07 to .37). Neurodevelopmental assessments in early childhood adapted cross-culturally are predictive of school-age neuropsychological cognitive ability.

Neurodevelopmental Outcomes of Children Following In Utero Exposure to Zika in Nicaragua

Background

Neurodevelopmental outcomes of asymptomatic children exposed to Zika virus (ZIKV) in utero are not well characterized.

Methods

We prospectively followed 129 newborns without evidence of congenital Zika syndrome (CZS) up to 24 months of age. Participants were classified as ZIKV exposed or ZIKV unexposed. The Mullen Scales of Early Learning (MSEL) was administered in the participants’ homes at 6, 12, 15, 18, 21, and 24 months of age by trained psychologists. Sociodemographic data, medical history, and infant anthropometry at birth were collected at each home visit. Our primary outcome was the Mullen Early Learning Composite Score (ECL) at 24 months of age between our 2 exposure groups. Secondary outcomes were differences in MSEL subscales over time and at 24 months.

Results

Of 129 infants in whom exposure status could be ascertained, 32 (24.8%) met criteria for in utero ZIKV exposure and 97 (75.2%) did not. There were no differences in maternal age, maternal educational attainment, birthweight, or gestational age at birth between the 2 exposure groups. The adjusted means and standard errors (SEs) for the ELC score between the ZIKV-exposed children compared to ZIKV-unexposed children were 91.4 (SE, 3.1) vs 96.8 (SE, 2.4) at 12 months and 93.3 (SE, 2.9) vs 95.9 (SE, 2.3) at 24 months. In a longitudinal mixed model, infants born to mothers with an incident ZIKV infection (P = .01) and low-birthweight infants (<2500 g) (P = .006) had lower composite ECL scores.

Conclusions

In this prospective cohort of children without CZS, children with in utero ZIKV exposure had lower neurocognitive scores at 24 months.

Elevated Cerebrospinal Fluid Tau Protein Concentrations on Admission Are Associated With Long-term Neurologic and Cognitive Impairment in Ugandan Children With Cerebral Malaria

BACKGROUND

Elevated concentrations of cerebrospinal fluid (CSF) tau, a marker of axonal injury, have been associated with coma in severe malaria (cerebral malaria [CM]). However, it is unknown whether axonal injury is related to long-term neurologic deficits and cognitive impairment in children with CM.

METHODS

Admission CSF tau concentrations were measured in 145 Ugandan children with CM and compared to clinical and laboratory factors and acute and chronic neurologic and cognitive outcomes.

RESULTS

Elevated CSF tau concentrations were associated with younger age, increased disease severity (lower glucose and hemoglobin concentrations, malaria retinopathy, acute kidney injury, and prolonged coma duration, all P < .05), and an increased CSF:plasma albumin ratio, a marker of blood-brain barrier breakdown (P < .001). Admission CSF tau concentrations were associated with the presence of neurologic deficits at hospital discharge, and at 6, 12, and 24 months postdischarge (all P ≤ .02). After adjustment for potential confounding factors, elevated log10-transformed CSF tau concentrations correlated with worse cognitive outcome z scores over 2-year follow-up for associative memory (β coefficient, -0.31 [95% confidence interval [CI], -.53 to -.10]) in children <5 years of age, and for overall cognition (-0.69 [95% CI, -1.19 to -.21]), attention (-0.78 [95% CI, -1.34 to -.23]), and working memory (-1.0 [95% CI, -1.68 to -.31]) in children ≥5 years of age (all P < .006).

CONCLUSIONS

Acute axonal injury in children with CM is associated with long-term neurologic deficits and cognitive impairment. CSF tau concentrations at the time of the CM episode may identify children at high risk of long-term neurocognitive impairment.

Evolving White Matter Injury following Pediatric Traumatic Brain Injury

This study is unique in that it examines the evolution of white matter injury very early and at 12 months post-injury in pediatric patients following traumatic brain injury (TBI). Diffusion tensor imaging (DTI) was acquired at two time-points: acutely at 6-17 days and 12 months following a complicated mild (cMild)/moderate (mod) or severe TBI. Regional measures of anisotropy and diffusivity were compared between TBI groups and against a group of age-matched healthy controls and used to predict performance on measures of attention, memory, and intellectual functioning at 12-months post-injury. Analysis of the acute DTI data using tract based spatial statistics revealed a small number of regional decreases in fractional anisotropy (FA) in both the cMild/mod and severe TBI groups compared with controls. These changes were observed in the occipital white matter, anterior limb of the internal capsule (ALIC)/basal ganglia, and corpus callosum. The severe TBI group showed regional differences in axial diffusivity (AD) in the brainstem and corpus callosum that were not seen in the cMild/mod TBI group. By 12-months, widespread decreases in FA and increases in apparent diffusion coefficient (ADC) and radial diffusivity (RD) were observed in both TBI groups compared with controls, with the overall number of regions with abnormal DTI metrics increasing over time. The early changes in regional DTI metrics were associated with 12-month performance IQ scores. These findings suggest that there may be regional differences in the brain's reparative processes or that mechanisms associated with the brain's plasticity to recover may also be region based.

A Z-score based method for comparing the relative sensitivity of behavioral and physiological metrics including cognitive performance, mood, and hormone levels

A method for assessing the relative sensitivity of research metrics is proposed and illustrated by comparing 18 outcome measures from a published study of the cognitive, mood, and hormonal effects of four different levels of stress induced by intense military training. Research on the human response to stress often assesses multiple disparate dependent measures. Selecting the most sensitive is difficult as formal methods to compare varied dependent measures have not been developed. The method first converts the outcome measures into standard scores (z-scores) and then compares them using analysis of variance to determine whether there are differences in how they assess the impact of graded levels of exposure to stress. The analysis detected various significant interactions in several measures and suggests self-report mood questionnaires were more sensitive to the stressors present in the study than the cognitive or hormonal measures which were used. These findings support the effectiveness of the z-score based method as a useful procedure for objectively evaluating the differential sensitivity of various metrics. This method could be useful for research on other independent variables when use of multiple assessment strategies is appropriate. It could be used for evaluating studies yielding conflicting results, such as those detecting effects on one parameter but not others. In such instances, cross-metric inconsistencies may be due to differential sensitivity of measurement strategies rather than actual differences in the effects of the independent-variable on the domains under investigation.

Evaluating Immunopathogenic Biomarkers During Severe Malaria Illness as Modifiers of the Neuropsychologic Benefits of Computer Cognitive Games Rehabilitation in Ugandan Children

BACKGROUND

We explored 3 immunopathogenic biomarkers collected during acute malaria illness as potential moderators of gains from a computerized cognitive rehabilitation training (CCRT) intervention.

METHOD

Von Willebrand Factor (vWF), tumor necrosis factor (TNF) and Regulated on Activation, Normal T Expressed and Secreted (RANTES) were assayed from plasma and cerebral spinal fluid (CSF) of children during acute severe malaria anemia or cerebral malaria. Two years after acute malaria illness, 150 surviving children and 150 nonmalaria community controls (CCs) from their households 6-12 years old entered a 3-arm randomized controlled trial of titrating and nontitrating CCRT against no CCRT. Tests of cognition [Kaufman Assessment Battery for Children (KABC)], Tests of Variables of Attention and Achenbach Child Behavior Checklist (CBCL) were administered before and after 24 CCRT sessions over a 3-month period, and at 1-year follow-up. Differences in outcomes by trial arms and biomarker levels were evaluated using linear mixed effects models.

RESULTS

Severe malaria survivors with lower levels of vWF, lower CSF levels of TNF and higher levels of plasma and CSF RANTES had better KABC cognitive performance after both titrating and nontitrating CCRT compared with no CCRT. For the CBCL, high plasma RANTES was associated with no benefit from either the titrating and nontitrating CCRT, whereas high TNF plasma was predictive of the benefit for both interventions. These biomarker moderating effects were not evident for CC children.

CONCLUSIONS

Severe malaria immunopathogenic biomarkers may be related to poorer long-term brain/behavior function as evidenced by diminished benefit from a computerized cognitive rehabilitation intervention.

Neuropsychological benefits of computerized cognitive rehabilitation training in Ugandan children surviving severe malaria: A randomized controlled trial

BACKGROUND

Computerized cognitive rehabilitation training (CCRT) may be beneficial for alleviating persisting neurocognitive deficits in Ugandan severe malaria survivors. We completed a randomized controlled trial of CCRT for both severe malaria and non-malaria cohorts of children.

METHODS

150 school-age severe malaria and 150 non-malaria children were randomized to three treatment arms: 24 sessions of Captain's Log CCRT for attention, working memory and nonverbal reasoning, in which training on each of 9 tasks difficulty increased with proficiency; a limited CCRT arm that did not titrate to proficiency but randomly cycled across the simplest to moderate level of training; and a passive control arm. Before and after 2 months of CCRT intervention and one year following, children were tested with the Kaufman Assessment Battery for Children, 2nd edition (KABC-II), computerized CogState cognitive tests, the Behavior Rating Inventory for Executive Function (BRIEF), and the Achenbach Child Behavior Checklist (CBCL).

RESULTS

Malaria children assigned to the limited-CCRT intervention arm were significantly better than passive controls on KABC-II Mental Processing Index (P = 0.04), Sequential Processing (working memory) (P = 0.02) and the Conceptual Thinking subtest (planning/reasoning) (P = 0.02). At one year post-training, the limited CCRT malaria children had more rapid CogState card detection (attention) (P = 0.02), and improved BRIEF Global Executive Index (P = 0.01) as compared to passive controls. Non-malaria children receiving CCRT significantly benefited only on KABC-II Conceptual Thinking (both full- and limited-CCRT; P < 0.01), CogState Groton maze chase and learning (P < 0.01), and CogState card identification (P = 0.05, full CCRT only). Improvements in KABC-II Conceptual Thinking planning subtest for the non-malaria children persisted to one-year follow-up only for the full-CCRT intervention arm.

CONCLUSION

For severe malaria survivors, limited CCRT improved attention and memory outcomes more than full CCRT, perhaps because of the greater repetition and practice on relevant training tasks in the absence of the performance titration for full CCRT. There were fewer significant cognitive and behavior benefits for the non-malaria children, with the exception of the planning/reasoning subtest of Conceptual Thinking, with stronger full- compared to limited-CCRT improvements persisting to one-year follow-up.

Neurocognitive testing in West African children 3-6 years of age: Challenges and implications for data analyses

OBJECTIVE

When testing African children with developmental and cognitive standardized tests from high-income countries (HIC), investigators are uncertain as to whether to apply the HIC norms for these tests when standardizing a child's raw-score performance on the basis of age. The present study compared the construct validity of both raw and HIC-based standardized scores for the Mullen Scales of Early Learning (MSEL) and the Kaufman Assessment Battery in Children - 2nd edition (KABC-II) for Beninese children in a rural setting from three to six years of age.

METHODS

Seventy-four children 3-4 yrs of age were assessed with the MSEL, and 61 eligible older children (5-6 yrs of age) were assessed with the KABC-II. Assessors spoke the instructions to the children and caregivers for the assessment items in the local language. The developmental quality of the home environment was evaluated with the Caldwell Home Observation for Measurement of the Environment (HOME) inventory, and a material possessions and housing quality checklist was used as a measure of socio-economic status (SES). Children's mothers were given the Raven's Progressive Matrices test (nonverbal cognitive ability), and the Edinburgh Postpartum Depression Scale (EPDS) (emotional wellbeing).

RESULTS

For the MSEL, the 4-yr old group performed significantly better than the 3-yr old group on both the raw and standardized score comparisons for all scales. These differences were attenuated when using standardized scores, although the MSEL standardized cognitive composite score was still highly significant between years of age. When comparing 5- to 6-yr olds on KABC-II subtest and global scale performance, comparisons between the raw and standardized mean score performances were much less consistent. Generally, 6-yr olds performed significantly better than 5-yr olds on the raw score comparisons on the KABC-II subtests, but not so for standardized scores. Parent-child interactions assessed through the HOME measure was associated with both raw and standardized MSEL cognitive composite score outcomes on a multiple regression analysis. SES was the only significant predictor for KABC-II raw and standardized outcomes.

CONCLUSION

Standardization using HIC norms was not optimal, resulting in minimal impact to account for age when using the MSEL, and lower scores for oldest children compared with youngest children when using the KABC2. This is likely due to children in Benin drifting away from HIC-based norms with each passing year of age, systematically lowering standardized performance measures. These findings support the importance of having a local comparison group of reference or control children to allow for adjusted (for age, HOME, and SES) raw score comparisons when using western-based tests for developmental and neuropsychological evaluation.

Early and middle childhood developmental, cognitive, and psychiatric outcomes of Malawian children affected by retinopathy positive cerebral malaria

The objective is to determine the short -and long-term developmental, cognitive, and psychiatric effects of retinopathy positive cerebral malaria (CM-R) among young children in a prospective study assessing them around the onset of disease and again 2 years at preschool and again at school age. In total, 109 children were recruited from the Queen Elizabeth Central Hospital in Blantyre, Malawi, (N = 49) with CM-R and non-malaria controls  (N = 60). Children were assessed for overall motor, language, and social skills using the Malawi Developmental Assessment Tool (MDAT) at preschool age. At school age, the same children were then given the Kaufman Assessment Battery for Children, second edition (KABC-II), which assessed global cognitive performancememory, and learning; as well as the Test of Variables of Attention (TOVA), which assessed attention. The Achenbach Child Development Checklist (CBCL) was administered at both time points to assess emotional and behavioral patterns. Controls scored significantly better on all KABC-II global domains as well as on the mental processing index than their CM-R group counterparts, but showed no performance differences in the TOVA and CBCL assessments at school age, or in the MDAT and CBCL assessments at preschool age. The MDAT total score was significantly correlated with the KABC-II sequential processing, learning, and mental processing index among CM-R survivors but not among controls. Persisting neurocognitive effects of CM can be captured with the KABC-II at school age. The MDAT at preschool age is correlated with the KABC-II among CM-R survivors and can be used to capture early emerging developmental deficits due to CM-R.

Validity of Neuropsychological Testing in Young African Children Affected by HIV

Introduction

Western-constructed neuropsychological tests have been used in low and middle income countries to assess the impact of HIV/AIDS and other chronic illnesses. We explore using such instruments cross-culturally in a sub-Saharan Africa setting.

Methods

IMPAACT P1104S was a two-year observational study carried out at six clinical sites (South Africa- 3 sites, Malawi, Uganda and Zimbabwe) to assess and compare neuropsychological outcomes in three cohorts of children 5-11 years of age: HIV-infected (HIV), HIV-exposed but uninfected (HEU) and HIV unexposed and uninfected (HU). Descriptive statistics compared socio-demographic characteristics among children at sites. Instruments included the KABC-II cognitive ability, TOVA attention/impulsivity, BOT-2 motor proficiency tests, and BRIEF executive function problems. Test characteristics were assessed using intraclass and Spearman non-parametric correlations, linear regression and principal factor analyses.

Results

Of the 611 participants, 50% were male and mean age ranged from 6.6 to 8 years. In Malawi, Uganda and Zimbabwe, substantial proportions of families lived in rural settings in contrast to the South African sites. Intraclass correlation coefficients between weeks 0 and 48 were highest for the KABC scores, ranging between 0.42 to 0.71.Correlations among similar test domains were low to moderate but significant, with positive correlation between KABC Sequential and TOVA scores and negative correlation between BRIEF and KABC scores. TOVA response time scores correlated negatively with the BOT-2 Total points score. Strong and significant associations between individual measures of growth, disability and development with all test scores were observed. Performance-based measures were markedly lower for HIV compared to HEU and HU participants, even after controlling for age, sex and site. Factor analyses confirmed the underlying theoretical structure of the KABC scaled item scores.

Conclusion

The KABC, TOVA, BRIEF and BOT-2 were valid and reliable tools for assessing the neuropsychological impact of HIV in four sub-Saharan African countries.

Cognitive Outcomes and Psychiatric Symptoms of Retinopathy-Positive Cerebral Malaria: Cohort Description and Baseline Results

Cerebral malaria (CM) is a common cause of death and disability among children in sub-Saharan Africa. Many prior studies of neuropsychiatric morbidity have been limited by a cross-sectional design or a short duration of follow-up. Most have included subjects who may have presented with coma due to a disease process other than CM. No studies have assessed the relationship between magnetic resonance imaging (MRI) findings and long-term outcomes. The Cognitive Outcomes and Psychiatric symptoms of retinopathy-positive CM (COPS) cohort is the first large (N = 221) prospectively recruited cohort of stringently defined cases of CM and hospital-based, age-matched, non-CM controls in whom cognitive and psychiatric outcomes are assessed with standardized measures semi-annually for up to 5 years. We report baseline characteristics of the cohort and outcomes at 1 month. At enrollment, CM cases were more likely to come from families with fewer socioeconomic resources and to have health characteristics that increase risk for malaria. In children younger than 5 years, cases were delayed in motor, language, and social development by approximately 6 months, compared with controls. More significant delays occurred in those with MRI abnormalities at the 1-month follow-up visit. There were no differences between cases and controls in inhibitory self-control, nor in cognitive function in children ≥ 5 years of age. The latter finding may be related to the smaller sample size, case-control imbalance in socioeconomic status, or the use of cognitive and behavioral assessments that are less culturally appropriate to this population. Continued follow-up will help determine predictors of long-term outcomes.

The feasibility of automated eye tracking with the Early Childhood Vigilance Test of attention in younger HIV-exposed Ugandan children

OBJECTIVE

Tobii eye tracking was compared with webcam-based observer scoring on an animation viewing measure of attention (Early Childhood Vigilance Test; ECVT) to evaluate the feasibility of automating measurement and scoring. Outcomes from both scoring approaches were compared with the Mullen Scales of Early Learning (MSEL), Color-Object Association Test (COAT), and Behavior Rating Inventory of Executive Function for preschool children (BRIEF-P).

METHOD

A total of 44 children 44 to 65 months of age were evaluated with the ECVT, COAT, MSEL, and BRIEF-P. Tobii ×2-30 portable infrared cameras were programmed to monitor pupil direction during the ECVT 6-min animation and compared with observer-based PROCODER webcam scoring.

RESULTS

Children watched 78% of the cartoon (Tobii) compared with 67% (webcam scoring), although the 2 measures were highly correlated (r = .90, p = .001). It is possible for 2 such measures to be highly correlated even if one is consistently higher than the other (Bergemann et al., 2012). Both ECVT Tobii and webcam ECVT measures significantly correlated with COAT immediate recall (r = .37, p = .02 vs. r = .38, p = .01, respectively) and total recall (r = .33, p = .06 vs. r = .42, p = .005) measures. However, neither the Tobii eye tracking nor PROCODER webcam ECVT measures of attention correlated with MSEL composite cognitive performance or BRIEF-P global executive composite.

CONCLUSION

ECVT scoring using Tobii eye tracking is feasible with at-risk very young African children and consistent with webcam-based scoring approaches in their correspondence to one another and other neurocognitive performance-based measures. By automating measurement and scoring, eye tracking technologies can improve the efficiency and help better standardize ECVT testing of attention in younger children. This holds promise for other neurodevelopmental tests where eye movements, tracking, and gaze length can provide important behavioral markers of neuropsychological and neurodevelopmental processes associated with such tests. (PsycINFO Database Record

Cerebral malaria retinopathy predictors of persisting neurocognitive outcomes in Malawian children

BACKGROUND

Neuropsychological sequelae from pediatric cerebral malaria (CM) have been well-documented. Although malaria-specific retinopathy during acute illness has become a defining criterion for CM, its relationship to neurocognitive sequelae has not been documented. This relationship is important if malaria-specific retinopathy reflects the possible brain neuropathogenesis leading to long-term neurocognitive deficits.

METHODS

From 2008 to 2012, 49 Malawian children 4.5-12 years of age surviving retinopathy-positive CM (CM-R) were tested 1-6 yrs after illness with the Kaufman Assessment Battery for Children, 2 edition, the tests of variables of attention and the Achenbach Child Behavior Checklist. In an observational study of a cohort of cerebral malaria survivors, these neurocognitive and behavioral outcomes were statistically related to types and severity of retinopathy measures, while controlling for age, sex, body mass index, socioeconomic status and time interval between illness and testing.

RESULTS

Worse scores for hemorrhages, papilledema, optic disk hyperemia, retinal whitening of macula and foveal annulus were associated with poorer Kaufman Assessment Battery for Children, 2 edition mental processing index and global scale scores. Disk hyperemia was also predictive of tests of variables of attention D prime overall attention performance (inattention) and commission errors (impulsivity). Few associations were found between retinopathy scores and Achenbach Child Behavior Checklist (emotional and behavioral) outcomes.

CONCLUSIONS

We are the first to report the relationship between severity of malaria-specific retinopathy during acute illness in CM survivors and persisting neurocognitive problems. These findings support earlier studies documenting that severity of retinopathy during acute illness is medically prognostic in CM survivors. We extend these findings to include long-term neurocognitive outcomes.

A probabilistic model in cross-sectional studies for identifying interactions between two persistent vector-borne pathogens in reservoir populations

BACKGROUND

In natural populations, individuals are infected more often by several pathogens than by just one. In such a context, pathogens can interact. This interaction could modify the probability of infection by subsequent pathogens. Identifying when pathogen associations correspond to biological interactions is a challenge in cross-sectional studies where the sequence of infection cannot be demonstrated.

METHODOLOGY/PRINCIPAL FINDINGS

Here we modelled the probability of an individual being infected by one and then another pathogen, using a probabilistic model and maximum likelihood statistics. Our model was developed to apply to cross-sectional data, vector-borne and persistent pathogens, and to take into account confounding factors. Our modelling approach was more powerful than the commonly used Chi-square test of independence. Our model was applied to detect potential interaction between Borrelia afzelii and Bartonella spp. that infected a bank vole population at 11% and 57% respectively. No interaction was identified.

CONCLUSIONS/SIGNIFICANCE

The modelling approach we proposed is powerful and can identify the direction of potential interaction. Such an approach can be adapted to other types of pathogens, such as non-persistents. The model can be used to identify when co-occurrence patterns correspond to pathogen interactions, which will contribute to understanding how organism communities are assembled and structured. In the long term, the model's capacity to better identify pathogen interactions will improve understanding of infectious risk.