Growth in early infancy drives optimal brain functional connectivity which predicts cognitive flexibility in later childhood.

Functional brain network organization, measured by functional connectivity (FC), reflects key neurodevelopmental processes for healthy development. Early exposure to adversity, e.g. undernutrition, affects neurodevelopment, observable via disrupted FC, and leads to poorer outcomes from preschool age onward. We assessed longitudinally the impact of early growth trajectories on developmental FC in a rural Gambian population from age 5 to 24 months. To investigate how these early trajectories relate to later childhood outcomes, we assessed cognitive flexibility at 3-5 years. We observed that early physical growth before the fifth month of life drove optimal developmental trajectories of FC that in turn predicted cognitive flexibility at pre-school age. In contrast to previously studied developmental populations, this Gambian sample exhibited long-range interhemispheric FC that decreased with age. Our results highlight the measurable effects that poor growth in early infancy has on brain development and the subsequent impact on pre-school age cognitive development, underscoring the need for early life interventions throughout global settings of adversity.

It takes a village: Caregiver diversity and language contingency in the UK and rural Gambia.

INTRODUCTION: There is substantial diversity within and between contexts globally in caregiving practices and family composition, which may have implications for the early interaction's infants engage in. We draw on data from the Brain Imaging for Global Health (BRIGHT, www.globalfnirs.org/the-bright-project) project, which longitudinally examined infants in the UK and in rural Gambia, West Africa. In The Gambia, households are commonly characterized by multigenerational, frequently polygamous family structures, which, in part, is reflected in the diversity of caregivers a child spends time with. In this paper, we aim to 1) evaluate and validate the Language Environment Analysis (LENA) for use in the Mandinka speaking families in The Gambia, 2) examine the nature (i.e., prevalence of turn taking) and amount (i.e., adult and child vocalizations) of conversation that infants are exposed to from 12 to 24 months of age and 3) investigate the link between caregiver diversity and child language outcomes, examining the mediating role of contingent turn taking. METHOD: We obtained naturalistic seven-hour-long LENA recordings at 12, 18 and 24 months of age from a cohort of N = 204 infants from Mandinka speaking households in The Gambia and N = 61 infants in the UK. We examined developmental changes and site differences in LENA counts of adult word counts (AWC), contingent turn taking (CTT) and child vocalizations (CVC). In the larger and more heterogenous Gambian sample, we also investigated caregiver predictors of turn taking frequency. We hereby examined the number of caregivers present over the recording day and the consistency of caregivers across two subsequent days per age point. We controlled for children's cognitive development via the Mullen Scales of Early Learning (MSEL). RESULTS: Our LENA validation showed high internal consistency between the human coders and automated LENA outputs (Cronbach's alpha's all >.8). All LENA counts were higher in the UK compared to the Gambian cohort. In The Gambia, controlling for overall neurodevelopment via the MSEL, CTT at 12 and 18 months predicted CVC at 18 and 24 months. Caregiver consistency was associated with CTT counts at 18 and 24 months. The number of caregivers and CTT counts showed an inverted u-shape relationship at 18 and 24 months, with an intermediate number of caregivers being associated with the highest CTT frequencies. Mediation analyses showed a partial mediation by number of caregivers and CTT and 24-month CVC. DISCUSSION: The LENA provided reliable estimates for the Mandinka language in the home recording context. We showed that turn taking is associated with subsequent child vocalizations and explored contextual caregiving factors contributing to turn taking in the Gambian cohort.

Executive functioning skills and their environmental predictors among pre-school aged children in South Africa and The Gambia.

Executive functions (EFs) in early childhood are predictors of later developmental outcomes and school readiness. Much of the research on EFs and their psychosocial correlates has been conducted in high-income, minority world countries, which represent a small and biased portion of children globally. The aim of this study is to examine EFs among children aged 3-5 years in two African countries, South Africa (SA) and The Gambia (GM), and to explore shared and distinct predictors of EFs in these settings. The SA sample (N = 243, 51.9% female) was recruited from low-income communities within the Cape Town Metropolitan area. In GM, participants (N = 171, 49.7% female) were recruited from the rural West Kiang region. EFs, working memory (WM), inhibitory control (IC) and cognitive flexibility (CF), were measured using tablet-based tasks. Associations between EF task performance and indicators of socioeconomic status (household assets, caregiver education) and family enrichment factors (enrichment activities, diversity of caregivers) were assessed. Participants in SA scored higher on all EF tasks, but children in both sites predominantly scored within the expected range for their age. There were no associations between EFs and household or familial variables in SA, except for a trend-level association between caregiver education and CF. Patterns were similar in GM, where there was a trend-level association between WM and enrichment activities but no other relationships. We challenge the postulation that children in low-income settings have poorer EFs, simply due to lower socioeconomic status, but highlight the need to identify predictors of EFs in diverse, global settings. RESEARCH HIGHLIGHTS: Assessed Executive Functioning (EF) skills and their psychosocial predictors among pre-school aged children (aged 3-5 years) in two African settings (The Gambia and South Africa). On average, children within each setting performed within the expected range for their age, although children in South Africa had higher scores across tasks. There was little evidence of any association between socioeconomic variables and EFs in either site. Enrichment activities were marginally associated with better working memory in The Gambia, and caregiver education with cognitive flexibility in South Africa, both associations were trend-level significance.

The Brain Imaging for Global Health (BRIGHT) Project: Longitudinal cohort study protocol.

There is a scarcity of prospective longitudinal research targeted at early postnatal life which maps developmental pathways of early-stage processing and brain specialisation in the context of early adversity. Follow up from infancy into the one-five year age range is key, as it constitutes a critical gap between infant and early childhood studies. Availability of portable neuroimaging (functional near infrared spectroscopy (fNIRS) and electroencephalography (EEG)) has enabled access to rural settings increasing the diversity of our sampling and broadening developmental research to include previously underrepresented ethnic-racial and geographical groups in low- and middle- income countries (LMICs). The primary objective of the Brain Imaging for Global Health (BRIGHT) project was to establish brain function - using longitudinal data from mother - for-age reference curves infant dyads living in the UK and rural Gambia and investigate the association between context-associated moderators and developmental trajectories across the first two years of life in The Gambia. In total, 265 participating families were seen during pregnancy, at 7-14 days, 1-, 5-, 8-, 12-, 18- and 24-months post-partum. An additional visit is now underway at 3-5 years to assess pre-school outcomes. The majority of our Gambian cohort live in poverty, but while resource-poor in many factors they commonly experience a rich and beneficial family and caregiving context with multigenerational care and a close-knit supportive community. Understanding the impact of different factors at play in such an environment ( i.e., detrimental undernutrition versus beneficial multigenerational family support) will (i) improve the representativeness of models of general cognitive developmental pathways from birth, (ii) identify causal pathways of altered trajectories associated with early adversity at both individual and group level, and (iii) identify the context-associated moderators ( i.e. social context) that protect development despite the presence of poverty-associated challenges. This will in turn contribute to the development of targeted interventions.