Effects of childhood poverty and chronic stress on emotion regulatory brain function in adulthood

A prevailing hypothesis about the association between income inequality and poor health is that inequality intensifies social hierarchies, increases stress, erodes social and material resources that support health, and subsequently harms health. However, the evidence in support of this hypothesis is limited by cross-sectional, ecological studies and a scarcity of developmental studies. To address this limitation, we used pooled, multilevel data from the Health Behaviour in School-aged Children study to examine lagged, cumulative, and trajectory associations between early-life income inequality and adolescent health and well-being. Psychosomatic symptoms and life satisfaction were assessed in surveys of 11-to 15-year-olds in 40 countries between 1994 and 2014. We linked these data to national Gini indices of income inequality for every life year from 1979 to 2014. The results showed that exposure to income inequality from 0 to 4 years uniquely predicted psychosomatic symptoms and lower life satisfaction after controlling lifetime mean income inequality, national per capita income, family affluence, age, and cohort and period effects.Income inequality from 5 to 9 years also related to symptoms and low life satisfaction in females.The cumulative income inequality exposure in infancy and childhood (i.e., average Gini index from birth to age 10) related to more symptoms and lower life satisfaction in adolescence. Finally, individual trajectories in early-life inequality (i.e., linear slopes in Gini indices from birth to 10 years) related to fewer symptoms and higher life satisfaction, indicating that earlier exposures mattered more to predicting adolescent health and wellbeing. These results help to establish the antecedent-consequence conditions in the association between income inequality and health and suggest that both the magnitude and timing of income inequality in early life have developmental consequences that manifest in reduced health and well-being in adolescence. M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT3 Keywords: Income inequality; adolescents; children; health; well-being; Health Behaviour in School-aged Children. M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT4 Early-life income inequality and adolescent health and well-being Socioeconomic contexts shape and constrain adolescent health and well-being (Chen & Paterson, 2006). Recent evidence suggests that socioeconomic differences in adolescent health have widened due to rising income inequality (Elgar et al., 2015; Viner et al., 2012). Income inequality also correlates with poor health and social outcomes (Kondo et al., 2009; Wilkinson & Pickett, 2010). An analysis of adolescent health in 34 mostly high-income countries found that national income inequality related to higher body mass indices, less physical activity, and more self-rated mental and physical health symptoms (Elgar et al., 2015). Other research on children and youth found that national or regional income inequality relates to poor self-rated health (Rözer ...

Convergent research suggests that childhood poverty is associated with perturbation in the stress response system. This might extend to aberrations in the connectivity of large-scale brain networks, which subserve key cognitive and emotional functions. Resting-state brain activity was measured in adults with a documented history of childhood poverty (n ¼ 26) and matched controls from middle-income families (n ¼ 26). Participants also underwent a standard laboratory social stress test and provided saliva samples for cortisol assay. Childhood poverty was associated with reduced default mode network (DMN) connectivity. This, in turn, was associated with higher cortisol levels in anticipation of social stress. These results suggest a possible brain basis for exaggerated stress sensitivity in low-income individuals. Alterations in DMN may be associated with less efficient cognitive processing or greater risk for development of stress-related psychopathology among individuals who experienced the adversity of chronic childhood poverty.

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