Early puberty and impulsivity partly explain why high family income protects less against marijuana use in Black youth
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.
Quick Facts
What This Study 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.
Key Numbers
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 They Did This
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.
Why This Research 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 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.
What This Study Doesn't 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.
Questions This Raises
- ?What drives earlier puberty onset in high-income Black youth?
- ?Would interventions targeting impulsivity during early puberty reduce the diminished returns effect?
Trust & Context
- Key Stat:
- Earlier puberty in high-income Black youth drove impulsivity and marijuana use
- Evidence Grade:
- Large nationally representative longitudinal study with SEM provides moderate evidence for a complex mediational pathway, limited by assumptions inherent in causal modeling.
- Study Age:
- 2025 publication from the ABCD Study with 6-year follow-up
- Original Title:
- Puberty Onset and Positive Urgency Explain Diminished Returns of Family Income on Tobacco and Marijuana Use.
- Published In:
- Open journal of psychology, 5(1) (2025)
- Authors:
- Assari, Shervin(3), Najand, Babak(3), Zare, Hossein
- Database ID:
- RTHC-05966
Evidence Hierarchy
Follows a group of people over time to track how outcomes develop.
What do these levels mean? →Frequently Asked Questions
Why would high income not protect Black youth equally?
The "Minorities' Diminished Returns" framework suggests that structural racism creates chronic stress that affects Black families regardless of income. This study found one biological pathway: high-income Black youth experienced earlier puberty, which increased impulsivity and substance use risk.
How does puberty timing affect substance use?
Earlier puberty onset was linked to higher positive urgency (a type of impulsivity), which in turn predicted earlier marijuana and tobacco initiation. This chain from biology to behavior may explain part of the racial disparity in substance use outcomes.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-05966APA
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
MLA
Assari, Shervin, et al. "Puberty Onset and Positive Urgency Explain Diminished Returns of Family Income on Tobacco and Marijuana Use.." Open journal of psychology, 2025. https://doi.org/10.31586/ojp.2025.1141
RethinkTHC
RethinkTHC Research Database. "Puberty Onset and Positive Urgency Explain Diminished Return..." RTHC-05966. Retrieved from https://rethinkthc.com/research/assari-2025-puberty-onset-and-positive
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.