Background: Electronic cigarette (e-cigarette) use and vaping tobacco have increased rapidly worldwide, raising concerns about their health effects, social acceptability, and regulatory challenges. In many countries, e-cigarettes are more commonly used by individuals from higher socioeconomic status (SES) backgrounds, who, in theory, should have greater knowledge about e-cigarettes and their associated risks. However, it remains unclear why a group with more knowledge about e-cigarette risks would also hold more positive attitudes toward vaping and exhibit higher usage rates — a phenomenon that may represent a knowledge-behavior paradox. Understanding this paradox, along with the complex relationships between e-cigarette knowledge, attitudes, and behaviors, is critical for informing effective public health interventions, campaigns, social media messaging, and regulatory policies. Objectives: This study aimed to evaluate the complex relationship between SES, e-cigarette knowledge, pro-vaping attitudes, and e-cigarette use. Methods: The SMOKES Study (Study of Measurement of Knowledge and Examination of Support for Tobacco Control Policies) used a multi-center, cross-sectional design, collecting data from 2,403 college and university students across 15 provinces in Iran (covering nearly half of the country's provinces). The survey measured family income, age, sex, ethnicity, e-cigarette use, knowledge, and attitudes. Structural Equation Modeling (SEM) was employed to examine the interrelations between SES, knowledge, attitudes, and behavior, while adjusting for age, sex, and ethnic minority status. Results: SEM analysis confirmed the hypothesized paradox. Although greater knowledge about e-cigarettes was linked to less favorable attitudes toward vaping and lower use, pro-vaping attitudes emerged as the strongest predictor of vaping behavior, while knowledge played a weaker protective role. Notably, individuals with higher SES simultaneously showed higher knowledge and, paradoxically, more pro-e-cigarette attitudes and greater usage. Female students and ethnic minority students reported higher correct knowledge and lower pro-vaping attitudes and use. Although age and higher family income were associated with more favorable attitudes, they did not directly predict vaping behavior. These results suggest that for higher SES individuals, poor knowledge is not the main driver of e-cigarette use; rather, their pro-e-cigarette attitudes, which seem to outweigh the influence of knowledge, play a key role. Conclusions: Although individuals from higher SES backgrounds report greater correct knowledge about e-cigarettes, this knowledge does not necessarily translate into reduced positive attitudes or lower usage. This study highlights the complexity of these paradoxical effects and suggests that public health strategies need to go beyond simple education and knowledge-based interventions. Targeted approaches should address industry messaging, challenge misconceptions, and strengthen regulatory efforts to reduce e-cigarette use among young adults, including those from higher SES backgrounds.

Background: As a central component of the brain's reward system, nucleus accumbens (NAcc) plays a crucial role in reward salience and substance use behaviors. Changes in the NAcc are also relevant to higher rates of substance use of youth and adults from low-income backgrounds. Although resting-state functional connectivity (rsFC) of the NAcc provides valuable insights into the neural mechanisms underlying reward processing and the propensity for self-reported reward salience and substance use, research exploring the association between NAcc rsFC and brain networks beyond the default mode network (DMN) and prefrontal cortex (PFC) is limited. Objective: To investigate the role of the resting-state functional connectivity of the NAcc with the cingulo-opercular network, sensorimotor mouth network, and sensorimotor hand network in the association between socioeconomic status, self-reported reward salience, and future substance use. Methods: Data were obtained from the Adolescent Brain Cognitive Development (ABCD) study. NAcc rsFC with the cingulo-opercular network, sensorimotor mouth network, and sensorimotor hand network was assessed at baseline. Socioeconomic status was measured using family income. Self-reported reward salience was assessed using validated psychometric scales. Substance use outcomes were tracked longitudinally over the study period. Structural Equation Modeling was employed to examine the covariances between family income, NAcc rsFC, reward salience, and subsequent substance use. Results: Higher baseline family income was positively associated with baseline NAcc rsFC (B = 0.092, p < 0.001) and negatively associated with baseline reward salience (B = -0.040, p = 0.036) and future substance use (B = -0.081, p < 0.001). Baseline NAcc rsFC was strongly and positively associated with reward salience (B = 0.734, p < 0.001) and future substance use up to age 13 (B = 0.124, p < 0.001). Additionally, baseline reward salience was positively associated with future substance use (Covariance = 0.176, p < 0.001). Conclusion: The findings suggest that NAcc rsFC with brain networks beyond the DMN or PFC may contribute to the links between low parental socioeconomic status, reward salience, and substance use risk. Expanding the understanding of NAcc rsFC provides new insights into the neural mechanisms underlying these associations. These results have important implications for developing targeted interventions aimed at preventing substance use, particularly among low-income youth with heightened reward salience. Further research is needed to explore causal pathways and moderating factors influencing these relationships.

Objective: To examine racial/ethnic differences in the associations of family socioeconomic status (SES), neighborhood SES, and inhibitory control with body mass index (BMI) in 9-10-year-old children using data from the Adolescent Brain Cognitive Development (ABCD) study. Methods: This cross-sectional study included a diverse sample of children aged 9-10 years, representing non-Latino White, Black, Latino, Asian, and Other racial/ethnic groups. BMI was the primary outcome. Key predictors were family SES, neighborhood SES, and inhibitory control. Multivariable regression models were stratified by race/ethnicity to identify group-specific associations. Results: Race/ethnic groups differed in psychosocial correlates of childhood BMI at age 9 and 10. Among non-Latino White children, higher family income (B = -0.086, p < 0.001), higher parental education (B = -0.069, p < 0.001), and living in a married household (B = -0.079, p < 0.001) were associated with lower BMI. Additionally, the presence of healthy food options in the zip code (B = -0.030, p = 0.032) was linked to lower BMI, while lack of planning (B = 0.032, p = 0.030) was associated with higher BMI. For non-Latino Black children, positive urgency (B = -0.068, p = 0.022) was negatively associated with BMI, while other factors such as family SES and neighborhood SES did not show significant associations. For Latino children, higher family income (B = -0.093, p = 0.001) and parental education (B = -0.099, p < 0.001) were associated with lower BMI. In this group, male gender (B = 0.043, p = 0.033) was associated with higher BMI. Among Asian children, higher family income (B = -0.199, p = 0.006) and parental education (B = -0.144, p = 0.037) were significantly associated with lower BMI. For children in the "Other" racial/ethnic category, higher family income (B = -0.101, p = 0.023), living in a married household (B = -0.076, p = 0.026), and higher median income in the zip code (B = -0.083, p = 0.013) were associated with lower BMI. In this group, male children had lower BMI compared to females (B = -0.089, p = 0.001). Conclusion: The findings highlight substantial racial/ethnic differences in the psychosocial and socioeconomic correlates of BMI in children. There is a need for tailored interventions that target social determinants of childhood high BMI. One size does not fit all.

Background: Parental education is a key determinant of academic performance, yet its protective effects may differ by race and ethnicity. The concept of Minorities’ Diminished Returns (MDRs) highlights the weaker association between socioeconomic resources and outcomes for marginalized populations, including Black and Latino youth. Objective: To investigate whether the positive association between parental education and school performance (letter grades) is weaker for Black and Latino youth compared to non-Latino White youth. Methods: Data were drawn from the Monitoring the Future (MTF) 2023 study. The sample included Black, Latino, and non-Latino White youth. The outcome was a nine-level continuous measure of academic performance based on self-reported letter grades, with higher scores indicating better performance. Multivariate regression models tested interactions between parental education and race/ethnicity in predicting grades, adjusting for confounders such as family income, gender, and school characteristics. Results: A total number of 7584 12^th graders entered the study. Parental education was positively associated with school performance across all groups, but the magnitude of this association was significantly smaller for Black and Latino youth compared to non-Latino White youth. Even after controlling for socioeconomic and contextual factors, the racial and ethnic differences in the strength of this association persisted. Conclusions: Our findings provide evidence of Minorities’ Diminished Returns (MDRs) in the academic domain, with Black and Latino youth experiencing weaker benefits of parental education on school performance. These disparities suggest that structural barriers and systemic inequities undermine the translation of parental educational attainment into academic success for marginalized groups. Policy interventions must address these structural barriers to promote equity in educational outcomes.

Background: Most neuroscience research has predominantly focused on White, middle-class populations, leading to gaps in understanding how socioeconomic status (SES) influences brain development and health behaviors in racially diverse groups. Tobacco use, a major public health concern, is influenced by both family and neighborhood SES, with early initiation during adolescence predicting long-term health outcomes. The Adolescent Brain Cognitive Development (ABCD) study provides a unique opportunity to examine racial disparities in the pathways from SES to brain development and behavior, especially through the lens of Marginalization-Related Diminished Returns (MDRs), where the effects of SES are attenuated for minority groups. Objective: This study investigates racial variation in the associations between SES, cerebral cortical volume, and tobacco use initiation, comparing Black and White youth over 4-6 years of follow-up. Methods: Data from the ABCD study were analyzed to assess pathways from family income to adolescents’ cortical volume via the needs-to-income ratio, and from cortical volume to tobacco use initiation. Structural equation modeling was used to evaluate these pathways, stratified by race, with a focus on comparing Black and White participants. Covariates included family and neighborhood SES, demographic factors, and baseline behavioral measures. Results: We found that the positive association between income (via the needs-to-income ratio) and total cortical volume was significantly weaker for Black youth compared to White youth. Additionally, the link between larger total cortical volume and reduced risk of tobacco initiation was also weaker in Black adolescents. These findings were consistent over 4-6 years of follow-up, suggesting that Black youth experience diminished returns from higher SES in terms of brain development and behavioral outcomes. Conclusions: Our findings highlight significant racial disparities in the pathways from SES to brain development and tobacco use initiation, supporting the Marginalization-Related Diminished Returns (MDRs) framework. While higher SES is associated with larger cortical volumes and lower tobacco use risk in White youth, these associations are attenuated in Black adolescents.

Background: Although some neural mechanisms underlying socioeconomic status (SES) disparities are known, the role of brain-wide resting-state functional connectivity in these effects remains less understood. Aim: This study aims to identify brain-wide resting-state functional connectivity signatures that may mediate the effects of SES on body mass index (BMI) and blood pressure in children, using data from the Adolescent Brain Cognitive Development (ABCD) study. Methods: Data were drawn from the ABCD study, a large, diverse cohort of children aged 9-10. Pre-processed resting-state functional MRI data were used, and factor analysis was conducted to extract a whole-brain connectivity factor. The first factor, capturing the greatest variance in brain-wide resting-state connectivity, was selected for further analysis in a structural equation model (SEM). This connectivity factor was tested as a potential mediator of the relationship between SES (measured by parental education, family income, and neighborhood characteristics) and two indicators of cardiometabolic health: BMI and systolic blood pressure. Results: Factor analysis revealed a robust first factor that accounted for a significant proportion of variance in brain-wide resting-state functional connectivity. This factor was significantly associated with SES, indicating that children from lower SES backgrounds exhibited distinct connectivity patterns. Additionally, the factor was linked to both BMI and systolic blood pressure, suggesting its relevance to cardiometabolic health. Mediation analysis showed that this connectivity factor partially mediated the relationship between SES and both BMI and systolic blood pressure. Conclusions: Brain-wide functional connectivity may be a mediator of SES effects on BMI and blood pressure in children. The first connectivity factor provides a promising neural signature linking SES with cardiometabolic risk. Comprehensive brain-wide approaches to functional connectivity may offer valuable insights into how social determinants of health shape neural and physical development in childhood.

Background: Puberty is a crucial developmental milestone that involves significant physiological, emotional, and behavioral changes. Early puberty onset, influenced by both biological and social factors, is associated with an increased risk of engaging in substance use, such as tobacco and marijuana. While high family income is generally linked to delayed puberty onset and lower behavioral risks, these benefits may not be equally protective for Black youth due to the phenomenon of Minorities' Diminished Returns (MDRs). MDRs suggest that higher family income does not offer the same protective effects for Black youth as it does for White youth, potentially leading to earlier puberty and increased substance use among high-income Black adolescents. Objective: This study aimed to investigate whether early puberty onset and associated positive urgency (impulsivity) mediate the relationship between family income and the initiation of tobacco and marijuana use over a six-year follow-up period among adolescents. Additionally, the study examined whether the effects of family income on early puberty onset differ by race, testing the hypothesis that high-income Black youth would experience earlier puberty onset compared to their high-income White peers. Methods: Data were sourced from the Adolescent Brain Cognitive Development (ABCD) Study. Participants were 9-10-year-old adolescents at baseline, followed over a period of six years. Structural equation modeling (SEM) was used to assess whether early puberty onset mediated the effects of family income on substance use behaviors. Interaction terms between race and family income were included to test whether the impact of family income varies by race. Results: Early puberty onset and associated positive urgency partially explained the relationship between family income and the initiation of tobacco and marijuana use. High-income Black youth showed earlier puberty onset compared to their White counterparts. Earlier puberty onset then predicted higher positive urgency. These factors, in turn, were linked to higher rates of tobacco and marijuana initiation. Conclusions: This study provides additional evidence that the benefits of high family income do not extend equally to Black adolescents, particularly regarding delaying puberty onset and its consequences for substance use.

Background: Minorities’ Diminished Returns (MDRs) theory posits that socioeconomic resources have weaker protective effects on health and behavior for racial and ethnic minorities compared to Whites. This study examines whether tobacco susceptibility, defined as curiosity, intention, and openness to future tobacco use, mediates the diminished returns of family income on tobacco initiation among Black adolescents. Methods: Data from the Adolescent Brain Cognitive Development (ABCD) Study were analyzed. Participants were followed from age 9 to 16. All participants were tobacco naïve at baseline. Tobacco susceptibility was assessed through self-reported measures of curiosity, intention, and openness to future tobacco use. Structural equation modeling (SEM) was used to examine the relationship between family income, tobacco susceptibility, and tobacco initiation. Results: Overall, 10,653 Black or White youth entered our analysis. The analysis revealed that higher family income was less effective in preventing tobacco initiation among Black adolescents. Tobacco susceptibility significantly predicted tobacco initiation and partially mediated the relationship between family income and tobacco initiation. Conclusions: Tobacco susceptibility explains some of the diminished returns of family income on tobacco initiation among Black adolescents. Interventions aimed at reducing tobacco susceptibility may enhance the protective effects of family income and help mitigate health disparities.