Biological, Behavioral, and Genetic Mechanisms in the Intergenerational Transmission of Toxic Stress - PROJECT SUMMARY/ABSTRACT:
The purpose of this Pathway to Independence Award is to prepare the applicant for an independent, sustained
program of research that incorporates biological, behavioral, and genetic concepts and methods to understand
and prevent toxic stress among vulnerable children and families. Toxic stress describes persistent elevation of
the hypothalamic-pituitary-adrenal (HPA) axis that occurs in response to childhood adversity (e.g. poverty,
maltreatment, parental mental illness), can be buffered by supportive caregiving, and leads to poor health and
development across the lifespan. Toxic stress can also be transmitted through generations, but the underlying
mechanisms of transmission are poorly understood. The research conducted in this study builds on NIH-
funded predoctoral research conducted by the applicant (F31NR016385), in which novel relationships between
mothers' childhood history (adversity and family strengths), current caregiving (caregiving responsiveness and
parental stress), and child indicators of toxic stress (biological, health, behavioral) were detected among
multiethnic, low-income maternal-child-dyads. Based on the importance of consistent sleep and circadian
rhythm patterns for healthy HPA-axis functioning, in the K99 phase the applicant will examine the feasibility of
using mother-child dyad actigraphy data to measure consistent daily routines (e.g. regular bedtimes, physical
activity) and test the hypothesis that caregivers can protect their children from toxic stress by providing daily
routine consistency. The K99 phase will include training in concepts and methods related to sleep/circadian
rhythm and gene-environment (GxE) interactions, as individuals are known to be differentially susceptible to
the effects of early childhood experiences. This training will be supported by expert mentorship and tailored
training experiences including coursework, directed readings, seminars, and scientific meetings. Informed by
relationships detected in the F31 and K99 phases of the study, in the R00 phase the candidate will examine
relationships among maternal childhood history, current maternal caregiving (consistent daily routines,
caregiving responsiveness, parental stress) and child indicators of toxic stress in a fully-powered sample of
multiethnic, low-income mother-child dyads (children age 3-4 years). Indicators of toxic stress will include
biological markers (e.g. hair cortisol, salivary cytokines) with which the candidate has prior expertise. The
candidate will also explore the extent to which genotypic variation in candidate genes related to caregiving
(OXTR, DRD4) and stress (BDNF, IL-6, FTO) contribute to mothers' and children's susceptibility to the effects
of early childhood experiences. The results of this study will be used by the candidate to further examine
intergenerational transmission of toxic stress and protective factors, and ultimately develop a precision health
intervention that aims to prevent toxic stress based on families' biobehavioral, genetic and environmental
characteristics.