Monthly payments of $333 rather than $20 shifted a measure in four-year-old children that is associated with the pace of aging in adults
Monthly payments of $333 rather than $20 shifted a measure in four-year-old children that is associated with the pace of aging in adults
On September 8, Nature Human Behaviour published results from the US Baby’s First Years trial. Families with newborns were randomly assigned to receive $333 or $20 per month. Four years later, measurements in 735 children showed lower DunedinPACE values in the group receiving the larger payment. DunedinPACE uses chemical marks on DNA to estimate the pace of age-related changes.
Family income is usually intertwined with housing conditions, nutrition, parental employment, and stress. To test the effect of the income difference itself, the researchers randomly assigned families to receive different payments. In 2018–2019, they enrolled a thousand mothers whose incomes fell below the official US poverty threshold. After their children were born, 400 families received $333 per month, and 600 received $20. Random assignment before payments began created two groups that differed in the amount they were assigned to receive. The trial registration documented this plan in advance.
When the children were four years old, 735 provided saliva samples. The researchers measured DNA methylation, chemical marks on DNA that regulate gene activity, and calculated DunedinPACE. This measure was originally developed using data from adults in Dunedin, New Zealand. Researchers measured the function of 19 body systems in the same people at ages 26, 32, 38, and 45, then linked the changes to DNA methylation. In adults, higher DunedinPACE values are associated with disease, disability, and mortality.
DunedinPACE was lower by 0,17 standard deviations in children whose families received the larger payment. Standard deviations are a statistical unit used to express differences between group means. Comparisons of other epigenetic measures in children and mothers showed no differences between the groups.
Random assignment allows the difference in DunedinPACE to be attributed to the assigned payment amount, rather than to the usual association between poverty and living conditions. In this trial, the early-life environment changed one measure based on DNA marks in four-year-old children.