Q#1) The paper by Weaver et al. and similar science outline precisely why I have chosen to focus my health disparities research and clinical, programmatic efforts on the perinatal period. The science now clearly backs up the premise that early life exposures, including maternal-offspring behaviors, have profound impacts across the life trajectory. This is why the public health impact of maternal depression and other forms of maternal mental illness or social disadvantage are so profound. In terms of which maternal behaviors matter the most or most closely parallel “licking and grooming,” I’m not sure we have a clear answer to this. Would probably fall into the broad categories of attachment, emotional co-regulation, emotional attunement, and physical contact promoted by breastfeeding and other snuggling. If anyone knows of studies in humans that clearly link the rat studies with maternal human behaviors, I’d love to know them. Otherwise, I think I have a lit review in my future…
Q#2) Studies like this are very hard, because it is difficult if not impossible to randomize maternal behavior and to account for all of the relevant confounders. There are cultural differences seen across the world in terms of how mothers relate and attach to their infants—co sleeping or no co sleeping, carrying infants to work or leaving them at home with nannies—that speak to the resilience of how “good enough” attachment is probably really good enough. Also, it would obviously unethical to “randomize” mother-infant pairs to any sort of deprivation of emotional bonding and attachment. The study I can think to attempt would be as follows:
Develop a prospective cohort of women who deliver infants at ZSFG, a safety net setting with lots of psychosocial risk. Provide baseline survey collecting a variety of social determinants variables including demographic info, maternal emotional wellbeing, depression, social supports, etc. Have new moms enter self-report data at regular intervals about their mood, interactions with infant. Primary outcomes could be maternal depression and infant development. If I had money would get saliva and hair and blood from moms and babies and measure cortisol, oxytocin, etc. with MRIs looking at the amygdala and frontal cortex. Then if I ruled the world I would follow them all longitudinally and measure things like school readiness, school performance, and the socio-emotional and physical development of the infants into adulthood. Then you get to see how they parent and bond with THEIR infants.
Q#3) I don’t think there is real conflict between the cumulative approach to social disadvantage or the sensitive periods. Both are true, both can work together. I think this is highlighted by Table 3 iin the Gruenewald paper where they show that disadvantage at all time points is related to later adult trajectories. They also state that the significance between the different time points was not statistically significant when directly contrasted.
Q#4) I’m biased because one of the authors, Tom Boyce, is a close mentor and a personal hero. I think that GxE interactions account for a whole heck of a lot of health disparities. The interesting questions, I think are about how to intervene and implement…