Scientists from Washington State University found that a mother’s behavior towards her 12-month-old baby may influence genes associated with regulating the body’s stress response.
Some research suggests that interactions between a mother and her infant may help shape the child’s emotional responses. For example, a 2009 study found that infants of depressed mothers showed low social engagement, less mature regulatory behaviors, and more negative emotions.
Although scientists speculate that how a person handles stress as an adult may be shaped in infancy, the mechanisms behind this are unclear.
However, researchers from Washington State University may have found a link between the quality of a mother’s behavior towards her infant and specific molecular processes in the child’s brain that shape the stress response.
In the study published in the American Journal of Human Biology, the research team examined 114 mother/infant pairs from the Avon Longitudinal Study of Parents and Children. The team analyzed whether the mother’s interactions with their 12-month-old infants were warm or cold while reading a picture book.
During the analysis, the scientists found that the range of warmth didn’t vary significantly. However, they labeled the "coldest" behavior as awkward or neutral in the study.
Then, the team compared the observed behavior with the children’s blood work when they were seven. Specifically, they examined the blood's epigenetic data — the molecular processes influencing gene behavior.
The scientists discovered that babies exposed to neutral or awkward behavior at 12 months showed methylation, or epigenetic changes, on the NR3C1 gene at age seven. This gene is linked to regulating the body’s stress response, including the production of cortisol, a stress hormone that triggers the fight or flight response.
The scientists say their findings suggest that even minor early social or emotional influences in infancy may shape epigenetic-related functions.
Still, the study authors note that the slight differences found in this study may indicate normal human variation, and it's difficult to determine the long-term effects. In addition, the children in the study could have experienced a variety of environments and interactions between 12 months and seven years that may have influenced NR3C1 methylation.
Moreover, methylation changes could result from overall parental behavior over time and not from one point in the infant’s development.
Though infancy is considered a developmentally sensitive period, the study authors say that further research is needed to clarify which aspects of the social–emotional environment impact NR3C1 methylation and whether methylation changes in infancy persist through childhood.
- Journal of the American Academy of Child & Adolescent Psychiatry. Maternal Depression and Anxiety Across the Postpartum Year and Infant Social Engagement, Fear Regulation, and Stress Reactivity.
- American Journal of Human Biology. Maternal–infant interaction quality is associated with child NR3C1 CpG site methylation at 7 years of age.