Substance use in pregnancy is a significant public health problem and is associated with adverse offspring neurodevelopmental and behavioral outcomes, including cognitive dysfunction, autism spectrum disorder, attention deficit hyperactivity disorder, and mood disorders. However, the mechanisms by which maternal substance use results in offspring neurodevelopmental morbidity remain largely unknown. Emerging evidence highlights maternal immune dysregulation as a plausible mechanism because the use of opioids, cannabis, and alcohol has been associated with immune activation, with subsequent effects on the dynamic interaction between the placental immune and serotonin system. Our study’s objectives are to determine the impact of maternal substance use on maternal immune activation and offspring neurobehavioral developmental trajectories, and to define the placenta’s role in mediating these associations. This study capitalizes on the 25-site NIH/NIDA HEALthy Brain and Child Development study (HBCD), the largest (~7500 mother/child dyads) long-term United States study of early brain and child development outcomes after maternal high-risk exposures, including substance use. It is part of the NIH’s Helping to End Addiction Long-term (HEAL) initiative to speed scientific solutions to the national opioid public health crisis. The NIH HEAL initiative bolsters research across NIH to improve treatment for opioid misuse and addiction. We propose to bridge the mechanistic gap between maternal substance use and known adverse child outcomes, by performing maternal immune profiling, and placental and cord blood immune and serotonin profiling in 400 pregnancies across 4 geographically diverse HBCD sites. These biological measures will be linked to maternal phenotyping, child brain imaging, and behavioral measures collected by the core HBCD study from 0-15 months of age. The complementary studies proposed here will create a biological link between the prenatal environment and postnatal outcomes that is absent from the HBCD core protocol. Our multidisciplinary team will quantify maternal inflammation and immune activation induced by exposure to maternal substance use through studies of maternal cytokines, T cells and monocytes (Aim 1). We will define the impact of maternal substance use on placental and fetal immune activation and fetoplacental serotonin signaling (Aim 2). Lastly, we will link maternal substance use to neonatal neuroinflammation, as assessed by a novel analytic method applied to existing HBCD MRI data. (Aim 3). Using statistical modeling, we will estimate the extent to which maternal-fetal immune activation, dysregulated serotonin signaling, and neonatal brain inflammation mediate observed associations between substance use and early child behavioral outcomes. Completion of these Aims will provide new mechanistic insights into the impact of maternal substance use on maternal, placental, and fetal immune activation, and help elucidate the influence of placental immune dysregulation and altered serotonin signaling on child neurodevelopmental morbidity. Results will guide screening and therapeutic strategies to mitigate adverse transgenerational impacts of maternal substance use.

NARRATIVE Substance use in pregnancy is common, and associated with adverse neuropsychiatric outcomes in offspring reflecting altered brain development, but the underlying mechanisms remain poorly understood. Our study will build on the 25-site NIH/NIDA HEALthy Brain and Child Development study (HBCD), which evaluates early brain and child development outcomes in ~7,500 maternal/child dyads, by determining how maternal substance use alters immune activation in the mother, and disrupts immune and neurotransmitter signaling in the placenta and umbilical cord blood. These experiments will elucidate the biological links between maternal substance use and offspring neurodevelopmental morbidity, a key step toward development of screening and therapeutic strategies to mitigate adverse transgenerational impacts of prenatal substance exposure.