Experimental Evidence of the Impact of Parental Income on Child Mental Health and Neuroimmune Function

Summary

Growing up in a lower-income family robustly predicts worse mental health in adolescence and early adulthood. How does variability in family income "get under the skin" of the developing child and via what mechanisms does it increase risk for mental illness? Moreover, could supplements to family income at critical developmental periods help to prevent later youth mental illness? To address these questions, we leverage an innovative existing double blind randomized controlled trial of 3-years of substantial income supplements to parents. By experimentally studying the impacts of these income supplements on families and subsequent youth development, we can examine causal pathways from family income to risk for mental illness via family stress and neuroimmune mechanisms in ways never done before. Moreover, by measuring the longer-term impact of 3 years of income supplements to parents on their child's neuroimmune signaling and risk for mental illness, we can examine the policy implications for child development of unconditional cash transfers to parents and identify how and for whom these supplements help. We will test these basic and translational questions in a sample of 1,200 youth with lower-income parents randomly assigned to receive either a substantial monthly income supplement or a minimal monthly supplement for 3 years, starting when youth were between age 5 - 14 years old. We will follow up with youth and their parent 1 - 2 and 3 - 4 years after the intervention and examine whether income supplements predict better youth mental health during adolescence, as well as whether factors like child age and neighborhood quality modulate intervention effects. Additionally, we explore family stress mechanisms through which the intervention may impact child mental health. Finally, we will measure peripheral inflammation (inflammatory biomarkers and classical monocytes) and use MRI to assess threat, reward, and regulatory neural activity and connectivity among 500 of these youth. Our central hypothesis is that income supplements will decrease family and youth stress and improve parenting, which will improve neuroimmune signaling and decrease risk for psychopathology. Moreover, these effects will remain years after termination of the transfers and be strongest among families who received the intervention earlier in the child's life. This research will provide timely, relevant public health knowledge that will help policy makers understand the longer-term brain, immune, and mental health impacts of cash transfers to parents, while also advancing the science of the sociocontextual and neuroimmune pathways through which variability in family income impacts risk for psychopathology.