Preschool is a sensitive period for the influence of maternal support on the trajectory of hippocampal development

Abstract

Building on well-established animal data demonstrating the effects of early maternal support on hippocampal development and adaptive coping, a few longitudinal studies suggest that early caregiver support also impacts human hippocampal development. How caregiving contributes to human hippocampal developmental trajectories, whether there are sensitive periods for these effects, as well as whether related variation in hippocampal development predicts later childhood emotion functioning are of major public health importance. The current study investigated these questions in a longitudinal study of preschoolers assessed annually for behavioral and emotional development, including observed caregiver support. One hundred and twenty-seven children participated in three waves of magnetic resonance brain imaging through school age and early adolescence. Multilevel modeling of the effects of preschool and school-age maternal support on hippocampal volumes across the three waves was conducted. Hippocampal volume increased faster for those with higher levels of preschool maternal support. Subjects with support 1 SD above the mean had a 2.06 times greater increase in total hippocampus volume across the three scans than those with 1 SD below the mean (2.70% vs. 1.31%). No effect of school-age support was found. Individual slopes of hippocampus volume were significantly associated with emotion regulation at scan 3. The findings demonstrate a significant effect of early childhood maternal support on hippocampal volume growth across school age and early adolescence and suggest an early childhood sensitive period for these effects. They also show that this growth trajectory is associated with later emotion functioning.maternal support | hippocampus | sensitive period | preschool | emotions

Mother nurture and the social definition of neurodevelopment

“…Maternal support at neither preschool nor school age emerged as a significant predictor of hippocampal volume, a finding consistent with cross-sectional studies showing that variations in maternal influences do not necessarily emerge as main effects in studies of neurodevelopment (2,3). However, the unique, longitudinal approach of Luby et al (1) reveals a compelling association between maternal support and hippocampal growth trajectories: hippocampal volume increased faster with age among subjects with higher levels of maternal support. In addition, hippocampal growth trajectories predicted emotional regulation, an important endophenotype for virtually all common mental disorders.…”

“…Sensitive periods for environmental signals are also regionally specific, which may explain the discrepancies noted by Luby et al (1) between their findings and those of others groups. For example, the authors note that Lupien et al (3) reported MRI findings with similarly aged subjects (mid-childhood), showing an association between postnatal maternal depression and the volume of the amygdala, but not the hippocampus.…”

“…Luby et al (1) compared the association of maternal support at preschool or school ages with hippocampal growth and found a significant association only for maternal support at the younger age, leading the authors to suggest "an early childhood sensitive period for these effects" (see also ref. 4).…”

“…Early childhood appears to be a sensitive period for the influence of maternal support on hippocampal growth rates (1,4). However, hippocampal plasticity endures throughout life in response to factors such as stress and physical exercise, as well as tasks that engage hippocampal activity (6).…”

“…Studies with rodents suggest so, but human brain development occurs within a more complex environmental context and over a longer period. In PNAS, Luby et al (1) report the results of a prospective, longitudinal study that examined the association of maternal support at preschool and school ages, with hippocampal volume using MRI at three time points. A strength of the study is the laboratorybased assessment of maternal support during mildly stressful conditions, which very nicely mimics the challenges parents regularly face in child rearing.…”