Poster #15 - Low Income Predicts Reduced Neural Response to Reward in Mexican-Origin Adolescents

• In Event: 3-053 - Poster Session 10
  In Poster Session: PS 10 Section - Biological Processes: Neuroscience and Genetics

Integrative Statement

Nearly half of children and adolescents live in poverty in the United States (Johnson & Noble, 2016), putting them at heightened risk for worse health outcomes (Evans, 2004). Growing up in low-income households is associated with long-term effects on physiological functioning (Evans, 2004). Additionally, these risks may be exacerbated for Latinx adolescents, who are more likely to live in poverty (Clauss-Ehlers & Levi, 2002).

Family income during childhood has been linked to altered brain structure and function in adolescence and adulthood (Brito & Noble, 2014; Johnson et al., 2016; Weissman, Conger, Robins, Hastings, & Guyer, 2018). Brain function may mediate effects of income on later health, including mental health (Swartz , Hariri, & Williamson, 2017; Weissman et al., 2018). Neural activation in the ventral striatum (VS) and medial prefrontal cortex (mPFC) to potential reward may play important roles in later depression and anxiety issues. Accordingly, the present study tested if income-to-needs ratio in adolescence predicts neural response to anticipated reward, in a sample of Mexican-origin youth.

Participants were recruited for a sub-study of the California Families Project, a 10-year, longitudinal study of 674 Mexican-origin youth and their families. The sub-study was designed to examine neurobiological mechanisms of depression in 229 participants. The current analyses included 193 adolescents (49% female; Mage at MRI scan = 17.16 years, SD = 0.41). Measures were mother-reported household income across 7 waves (ending with wave 7; 11th grade), adolescent demographics (age, sex, number of years of substance use), and a functional magnetic resonance imaging (fMRI) scan during the Monetary Incentive Delay task (Knutson, Westdorp, Kaiser, & Hommer, 2000), measuring reward anticipation. Analyses involved regression models, all controlling for covariates of sex, age, and number of years that adolescents had previously reported using substances.

Results indicated that income-to-needs ratio was significantly associated with neural response to anticipated reward, in both the VS (Figure 1) and mPFC (Figure 2). These two regions, however, differed in several important ways. First, there was an interaction between sex and income on VS activation, such that female adolescents showed a stronger link (Figure 1). Further, running the same model separately on males and females revealed that girls displayed this pattern of income and VS response (β = 0.08, p = .001, R2 = .388, ΔR2 = .11), whereas males did not (β = 0.02, p = .36, R2 = .124, ΔR2 = .008). Second, mPFC response did not differ by gender, and was predicted by income for all adolescents (Figure 2).

Discussion will center on the role that poverty plays in neural development during adolescence, and how these associations differ by sex in important ways. Overall, low income appears to influence hypoactivity in medial prefrontal areas of the brain, and hypoactivity in reward regions for girls (but not for boys). Adolescent girls of Mexican origin who grow up in low-income households may be especially vulnerable to developing depression. The broader implications of these findings, such as contributions toward individually-tailored intervention strategies, will also be discussed in this presentation.

Authors

• Sarah Jean Beard, University of California, Davis
  Presenting Author

• Amanda Guyer, University of California, Davis
  Non-Presenting Author

• Richard W. Robins, University of California, Davis
  Non-Presenting Author

• Paul Hastings, University of California, Davis
  Non-Presenting Author

• Johnna R Swartz, University of California, Davis
  Non-Presenting Author