Research Aim:
Biological Embedding
Merrill Epigenetics and Psychosocial Intervention (EPI) Lab
Characterizing Biological Associations with Social Experiences
Early social experiences are associated with long-lasting effects in physiology, development, health, and well-being. One potential explanation of this is the “biological embedding” of these experiences into an individual’s molecular landscape that can relate to later expressions of vulnerability and resilience (as reviewed in Merrill, Gladish & Kobor, 2019 Current Topics in Behavioural Neurogenomics and Gladish, Merrill & Kobor, 2022 Current Environmental Health Reports). Due to the temporal and experiential plasticity, as well as the chemical stability of DNA methylation, this molecular tag provides a fruitful avenue to examine how social environments can get “under the skin”. In one project in collaboration with Dr. Nicole Letourneau (U of Calgary) and the Alberta Pregnancy Outcomes and Nutrition (APrON) cohort, we were able to discern and compare the DNA methylation of secure attachment, often associated with effective and sensitive caregiving, with insecure attachment styles as determined by the Strange Situation Procedure (Merrill, 2021, Attachment and Human Development).
It was during Dr. Merrill’s doctoral training at Cornell University with Dr. Cindy Hazan that she discovered her passion for attachment. She views it as a dynamic, biologically based system that motivates individuals to seek proximity to their caregiver to ensure their safety and results in a relatively persistent pattern of interpersonal behavior. They found that children with attachment that reflected a positive social environment had differential DNA methylation regions associated with immune function and propagation of immune cells, as well as cognitive development and long-term potentiation. An in-preparation follow-up to these findings in a different tissue, buccal epithelial cells from cheek swabs, examined disorganized attachment, often associated with fear of a caregiver, which reflected the current literature on adverse early environment – including overlapping findings with studies on child maltreatment, child labor camps, and a replication of our findings with retrospective accounts of childhood trauma in the cheek swabs of 18-year-olds in the Wisconsin Study of Families and Work cohort. We hope our follow-up with the APrON children (Co-Investigator), now age 14, will allow us to investigate if these biological signals of childhood maltreatment and the behavioral patterns with which they associated are maintained into adolescence.
Another example of how we can examine social environments from an epigenetic lens is a different collaboration with Dr. Letourneau examining paternal adverse childhood events (ACEs) and the signal of this early adversity in the DNA methylation in their infant offspring. We found the differences in infant DNA methylation that associated with more paternal ACEs, also related to sleep latency – potentially indicating a biological transmission of trauma through disrupted sleep patterns. To further elucidate the interaction of parenting, sleep, and DNA methylation, we are currently investigating the association of sleep and caregiver relationship with DNA methylation in children from the Conditions Affecting
Neurocognitive Development and Learning in Early Childhood (CANDLE) cohort, a unique Memphis longitudinal birth cohort, in collaboration with Dr. Nicole Bush (UCSF) and Dr. Alicia Smith (Emory). Together, this work and future studies that will undoubtedly stem from these findings, will elucidate a clearer picture of the molecular associations with childhood parenting experiences across the lifespan.
We are Recruiting!
Are you passionate about understanding how early adversity, biology, and the environment interact to shape behavior and health? Explore the intersection of genes and environment with us.
Please reach out if you are interested in joining the team!
Land Acknowledgement
Our lab acknowledges that the land we live, work, learn, and commune on is the original homelands of the Pennacook communities with the Pawtucket Village and Wamesit Village. We acknowledge the painful history of genocide and forced removal from this territory, and we honor and respect the many diverse Indigenous peoples still connected to this land on which we gather.