Weekly cannabis use and depressive symptoms in childhood were each independently associated with accelerated DNA methylation aging from adolescence to adulthood, with combined effects equivalent to 3-4 extra years of biological aging.
People interested in long-term biological effects of cannabis use during adolescence.
3-4 extra years of biological aging from combined risk factors
What the researchers found
Weekly cannabis use was significantly associated with accelerated DNA methylation aging (b=1.665, p=.005), as were years of weekly use (b=0.718, p=.012) and depressive symptoms (b=0.314, p=.014). In combined models, the cumulative effect of mental health symptoms, substance use, and adversity was equivalent to 3.17-3.76 additional years of biological aging.
Why it matters
Accelerated biological aging is linked to earlier onset of age-related diseases. Finding that cannabis use and depression independently speed up this process suggests early intervention on both fronts could have long-term health benefits.
The numbers in context
381 participants tracked from adolescence to adulthood. 1,950 total childhood assessments. Weekly cannabis use: b=1.665 (p=.005). Years of weekly use: b=0.718 (p=.012). Depression: b=0.314 (p=.014). Combined effect: 3.17-3.76 years of accelerated aging.
How the study worked
Longitudinal study of 381 participants from the Great Smoky Mountains Study. DNA methylation was measured from blood in adolescence (mean age 13.9) and adulthood (mean age 25.9). Childhood mental health, substance use, and adversity were assessed through 1,950 structured diagnostic interviews with participants and parents.
What this study cannot tell us
Blood-based DNA methylation may not reflect brain-specific changes. Observational design cannot prove causation. Sample is from a single US community (Appalachian). Methylation aging clocks are estimates, not direct measures of biological age.
How to read the evidence
Well-designed longitudinal study with objective biological measure and extensive childhood assessments. Limited by single-community sample and observational design.
When this study was published
Published in 2024 in the Journal of the American Academy of Child and Adolescent Psychiatry.
The bigger picture
This study bridges the gap between childhood experiences and adult biological outcomes. The finding that cannabis and depression independently accelerate aging through the same biological mechanism (DNA methylation) suggests a shared risk pathway that compounds over time.
Questions still open
- Is the accelerated aging reversible if cannabis use and depression are treated? Do different cannabis use patterns (frequency, potency, age of onset) have different effects on methylation aging? Would similar findings emerge in a more diverse population?
Common questions
Does cannabis age you faster?
What is DNA methylation aging?
Read the original research
The Impact of Childhood Mental Health and Substance Use on Methylation Aging Into Adulthood.
Journal of the American Academy of Child and Adolescent Psychiatry, 63(8), 825-834
Citation
Clark, Shaunna L; McGinnis, Ellen W; Zhao, Min; Xie, Linying; Marks, Garrett T; Aberg, Karolina A; van den Oord, Edwin J C G; Copeland, William E. (2024). The Impact of Childhood Mental Health and Substance Use on Methylation Aging Into Adulthood.. Journal of the American Academy of Child and Adolescent Psychiatry, 63(8), 825-834. https://doi.org/10.1016/j.jaac.2023.10.014
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