Multigenerational adversity impacts on gut microbiome composition and socioemotional functioning in early childhood

Both prenatal and postnatal exposure to early life adversity is associated with increased risk for psychopathology. The impacts of those adversity exposures can also persist across generations, although the mechanisms for intergenerational transmission remain unclear. Emerging evidence from non-human animal models suggests that the gut microbiome (the collection of microorganisms living in the gastrointestinal tract) may be a biological mechanism underlying those increased transmitted risks, but this hypothesis has not been directly tested in humans. In a sample of 450 mother-child dyads, we examined how three adversity exposures experienced across two generations: maternal childhood maltreatment (generation 1), maternal prenatal anxiety (generation 1 and 2), and children’s exposure to stressful life events (generation 2), as well as the accumulation of adversity exposure across these time points, is associated with children’s gut microbiome composition at 2 years of age (generation 2). We then explored associations between second generation children’s gut microbiome at 2 years of age and socioemotional functioning at 2 and 4 years of age. We found distinct differences in gut microbiome composition as a function of each adversity exposure, some of which overlapped with microbiome profiles associated with concurrent and prospective child socioemotional functioning. These results highlight an intergenerational impact of adversity on the microbiome of children that may increase their vulnerability to future mental illness. That several of these taxonomic differences may reflect shared functional impacts, e.g. on immune system regulation, across adversity exposures, motivates future research characterizing microbiome functional potential in the context of intergenerational adversity.