Epigenetic correlates of neonatal contact in humans

Abstract

Animal models of early postnatal mother-infant interactions have highlighted the importance of tactile contact for biobehavioral outcomes via the modification of DNA methylation (DNAm). The role of normative variation in contact in early human development has yet to be explored. In an effort to translate the animal work on tactile contact to humans, we applied a naturalistic daily diary strategy to assess the link between maternal contact with infants and epigenetic signatures in children 4-5 years later, with respect to multiple levels of child-level factors, including genetic variation and infant distress. We first investigated DNAm at four candidate genes: the glucocorticoid receptor gene, nuclear receptor subfamily 3, group C, member 1 (NR3C1), μ-opioid receptor M1 (OPRM1) and oxytocin receptor (OXTR; related to the neurobiology of social bonds), and brain-derived neurotrophic factor (BDNF; involved in postnatal plasticity). Although no candidate gene DNAm sites significantly associated with early postnatal contact, when we next examined DNAm across the genome, differentially methylated regions were identified between high and low contact groups. Using a different application of epigenomic information, we also quantified epigenetic age, and report that for infants who received low contact from caregivers, greater infant distress was associated with younger epigenetic age. These results suggested that early postnatal contact has lasting associations with child biology.

Maternal caregiving and DNA methylation in human infants and children: Systematic review

“…Eight studies analyzed how maternal behavior can be a predictor of a certain outcome . The remaining three assessed the role of maternal behavior in interaction with early adversities and/or epigenetic regulation .…”

“…A summary of each study timeline is reported in Figure . Five papers had a prospective study design while the other six had a retrospective study design. Adult studies were included only if they retrospectively investigated the link between adversity in infancy or childhood and epigenetic markers later in life.…”

“…Adult studies were included only if they retrospectively investigated the link between adversity in infancy or childhood and epigenetic markers later in life. Maternal caregiving was assessed either with self‐report tools or observational measures …”

“…Moore et al conducted a first longitudinal study in which they assessed the influence of maternal behavior (ie, diary in which they were to report infant fussing, unsuitable crying, feeding, sleeping and any caregiving behaviors such as carrying or holding, calculated in hours) on DNA methylation. Maternal behavior was assessed with a diary in which mothers reported for four consecutive days any caregiving carrying or holding that involved physical contact.…”

“…It has been long suggested the presence of developmental sensitive periods in which environmental factors have greater probabilities of affecting long‐term outcomes through epigenetic mechanisms . The studies reviewed here focused on different age periods during which protective caregiving took place: prenatal period, first months of life (5 weeks; 3 months; 4 months), toddlerhood (3 years), pre‐adolescence and a broader range of time up until adolescence (0‐16 years) and they all reported on short‐ and long‐term effects on a set of diverse developmental outcomes. On the one hand, these findings may be suggestive that maternal care variations have a significant effect on infants' DNA methylation independently from infant's age.…”