From the moment a child is born, a mother’s love and care are crucial for their physical and mental development, especially during the critical early stages of infancy. The environment and experiences children encounter during these formative years can have a lasting impact on their biology and health, even influencing future generations.
Recently, a study out of Washington State University (WSU) has added to our understanding of the crucial role played by mothers. The study found that a mother’s behavior toward her one-year-old baby is linked to an epigenetic change on a gene called NR3C1, which regulates the body’s stress response. Notably, this change was observed in the children when they reached the age of seven.
“There is evidence of a relationship between the quality of maternal-infant interaction and methylation of this gene – though these are small effects in response to a relatively small variation in interaction,” said biological anthropologist and lead author Elizabeth Holdsworth. However, she noted that the slight variation detected could also be a result of typical human diversity, making it difficult to ascertain any lasting effects.
In previous articles, we have discussed how severe stress in early life, such as neglect and abuse, can correlate with various epigenetic changes in adults. We have also shown how a mother’s care for her child can leave a lasting positive epigenetic impact on the baby’s long-term health.
The current study focused on a cohort of 114 predominantly white, middle-class mother-infant pairs from the Avon Longitudinal Study of Parents and Children. The researchers examined observational data collected during the mothers’ reading of picture books to their one-year-old infants born in the early 1990s. The objective was to investigate whether minor variations in social interaction, classified as “neutral” or “awkward” behavior, were associated with epigenetic changes.
The findings were based on a comparison between the mothers’ observational data and epigenetic data derived from their children’s blood at the age of seven. The results showed that children of mothers who exhibited “neutral” or “awkward” behavior were more prone to increased NR3C1 methylation. This gene encodes a glucocorticoid receptor that performs a critical function in controlling the hypothalamic-pituitary-adrenal (HPA) axis. This complex system releases stress hormones like cortisol and adrenaline in response to various stimuli, including real dangers or merely watching a horror movie or engaging in exercise.
While the NR3C1 gene is involved in activating the HPA axis, Holdsworth and her team believe that further research is needed to fully comprehend how methylation of this gene is associated with a stress response. They acknowledge that some studies have suggested increased DNA methylation is linked to blunted response, while others suggest hyper-reactivity.
“Within developmental biology, we know humans grow to fit the environment that they’re in, which contributes to normal human biological variation – it’s not necessarily good or bad,” adds Holdsworth. However, this knowledge could ultimately help us address and potentially prevent negative health outcomes related to early life experiences.
As ongoing research continues to investigate the mechanisms behind these changes, they hope to gain a deeper understanding of the critical period of development that occurs during infancy and how even the slightest changes during this stage can affect an individual in adulthood.
Source: E.A. Holdsworth et al. Maternal–infant interaction quality is associated with child NR3C1 CpG site methylation at 7 years of age. American Journal of Human Biology, February 13, 2023.
Reference: Sara Zaske. Small differences in mom’s behavior may show up in child’s epigenome. Washington State University. March 2, 2023.