Is Neurodevelopmental Assessment in Early Childhood Predictive of Performance Assessed Later in Childhood and Adolescence in Sub-Saharan Africa? A Systematic Review of the Literature

International audienceBackground - Most neurodevelopmental tests used to assess child development in sub-Saharan Africa were developed in western or high-income countries, raising the question of their usefulness with African children.Objective - This systematic review identified and synthesized key findings from studies measuring development in children in Sub-Saharan Africa in early childhood and again at school age, to assess neurocognitive associations longitudinally from infancy through middle childhood.Methods - The study was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses method, selecting articles referenced in the PubMed, PsycInfo, and Embase databases using the following inclusion criteria: published between 2000 and 2022, written in French or English, and presenting results dealing with the objective assessment of child’s neurodevelopment. All articles were registered in the Zotero reference manager and analyzed by title, abstract, and full text. Results - Several of the seven selected studies confirmed that attention and working memory in infancy can predict children’s neurocognitive performance, including mathematical ability, at school age. In two of the studies, children with poor mental development at 1 year of age are more likely to present with poorer behavioral development at school age, including learning difficulties in school and risk for grade repetition.Conclusion - Cognitive ability assessed in early childhood is strongly associated with performance at school age in cohorts of African children followed longitudinally. Even with assessments adapted cross-culturally, infants and preschoolers at risk for poor developmental outcomes can be identified to better receive strategic early interventions to enhance their development

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

International audienceObjectiveWhen 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.MethodsSeventy-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).ResultsFor 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.ConclusionStandardization 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

Prenatal iron deficiency, neonatal ferritin, and infant cognitive function

OBJECTIVE: To investigate the impact of prenatal maternal iron deficiency (ID) on cord blood serum ferritin (CBSF) concentration and infant cognitive and motor development. METHODS: Our prospective cohort study included 636 mother-singleton child pairs from 828 eligible pregnant women who were enrolled during their first antenatal care (ANC) visit in Allada, Benin, into a clinical trial comparing the efficacy of mefloquine and sulfadoxine-pyrimethamine. Venous blood samples of women were assessed for ferritin and hemoglobin concentrations at the first and second ANC visits (occurring at least 1-month apart) and at delivery. Women were prescribed daily iron and folic acid supplements throughout pregnancy. Hematologic examinations were repeated for cord blood at birth. At age 1 year, cognitive and motor functions of children were assessed by using the Mullen Scales of Early Learning. RESULTS: The prevalence of prenatal ID at first and second ANC visits, and at delivery was 30.5%, 34.0%, and 28.4%, respectively. CBSF concentrations were similar between ID and non-ID pregnant women. Neither prenatal ID nor CBSF concentration was associated with poor cognitive or gross motor function of children at age 1 year. CBSF concentrations were lower among mothers who had ID anemia (IDA) at delivery compared with non-IDA pregnant women (adjusted mean difference: –0.2 [95% confidence interval: –0.4 to –0.0]). CONCLUSIONS: In a malaria-endemic region, ID in pregnancy in the context of iron supplementation is neither associated with CBSF concentration nor with infant cognitive and motor development. Prenatal IDA around the time of delivery is associated with lower CBSF concentrations

Follow-Up of Elevated Blood Lead Levels and Sources in a Cohort of Children in Benin

International audienceLead exposure is associated with poor cognitive development in children. Very few studies in sub-Saharan Africa (SSA) have studied blood lead levels (BLLs) and non-gasoline sources of exposure in children. Data from a birth cohort in Benin (2011-2013) suggested that 58% of 1-year-old children had BLLs > 50 ug/L. We aimed to investigate the prevalence of elevated BLLs (>50 mu g/L and >100 mu g /L) among 425 of these children at 6 years of age in 2016-2018 and to compare BLLs between age 1 and 6 years, and study sources of lead at age 6 years. BLLs were analysed by inductively coupled plasma mass spectrometry. Multiple linear regression and quantile regressions were used to study potential sources of lead. The prevalence of BLLs > 50 mu g/L in children was 59.5% (Geometric Mean (GM) 56.4 mu g/L, 95% CI: 54.1-58.7) at 6 years of age compared to 54.8% (GM 56.5 mu g/L, 95% CI: 53.4-59.6) at 1 year of age. The prevalence of children with BLLs > 100 mu g/L decreased from 14.4% at 1 year of age to 8.2% at 6 years of age. After adjustment for all other covariates, consumption of peanuts more than once per month was significantly associated with a 22.0% (95% CI: 4.6, 42.5) increment in BLLs at age 6 years compared with no consumption. Consumption of bushmeat killed by lead bullets at age 6 years was associated with an increase in the higher percentiles of BLLs (P75) compared with the absence of this source. Other potential sources of lead associated with BLLs with marginal significance were consumption of rice, paternal occupational exposure, and the presence of activity with the potential use of lead. This prospective cohort confirms the persistently high prevalence of elevated BLLs in children residing in a rural region in the south of Benin, as well as the presence of multiple and continuous sources of lead. These results highlight the need for prevention programs to reduce and eliminate lead exposure in children