In the ABCD Study, high-income Black youth experienced earlier puberty onset than high-income White peers, which increased impulsivity and marijuana initiation, partially explaining why income is less protective for Black adolescents.
Health disparities researchers, developmental psychologists, substance use prevention researchers
Earlier puberty in high-income Black youth drove impulsivity and marijuana use
What the researchers found
Early puberty onset and associated positive urgency (impulsivity) partially mediated the relationship between family income and marijuana use initiation over six years. Critically, high-income Black youth showed earlier puberty onset compared to their White counterparts, and earlier puberty predicted higher impulsivity, which in turn predicted higher marijuana and tobacco initiation rates.
Why it matters
The "Minorities' Diminished Returns" framework explains why socioeconomic advantages protect Black youth less than White youth. This study identifies a biological pathway (earlier puberty leading to impulsivity) that partly explains this disparity, with implications for understanding racial health inequities.
The numbers in context
ABCD Study; ages 9-10 at baseline, 6-year follow-up; high-income Black youth had earlier puberty; earlier puberty predicted higher positive urgency; positive urgency predicted marijuana and tobacco initiation
How the study worked
ABCD Study data with 9-10-year-old participants followed for six years. Structural equation modeling assessed whether early puberty mediated effects of family income on substance use. Race-by-income interaction terms tested differential effects.
What this study cannot tell us
SEM models assume causal ordering that may not reflect reality. Puberty timing is influenced by many factors beyond those measured. Self-reported substance use may be underreported. The concept of "Minorities' Diminished Returns" is debated in the literature.
How to read the evidence
Large nationally representative longitudinal study with SEM provides moderate evidence for a complex mediational pathway, limited by assumptions inherent in causal modeling.
When this study was published
2025 publication from the ABCD Study with 6-year follow-up
The bigger picture
Racial disparities in substance use cannot be fully explained by socioeconomic factors alone. This study reveals that biological stress responses (reflected in earlier puberty timing) may translate structural racism into substance use risk, even among economically advantaged Black families.
Questions still open
- What drives earlier puberty onset in high-income Black youth? Would interventions targeting impulsivity during early puberty reduce the diminished returns effect?
Common questions
Why would high income not protect Black youth equally?
How does puberty timing affect substance use?
Read the original research
Puberty Onset and Positive Urgency Explain Diminished Returns of Family Income on Tobacco and Marijuana Use.
Open journal of psychology, 5(1)
Citation
Assari, Shervin; Najand, Babak; Zare, Hossein. (2025). Puberty Onset and Positive Urgency Explain Diminished Returns of Family Income on Tobacco and Marijuana Use.. Open journal of psychology, 5(1). https://doi.org/10.31586/ojp.2025.1141
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