In the ALSPAC birth cohort of 6,049 participants, childhood externalizing disorders at age 10 predicted early-onset high (RR=2.82), late-onset high (RR=1.62), and early-onset low (RR=1.82) cannabis problem trajectories from ages 15-24.
Child psychologists, prevention researchers, pediatricians, and school counselors.
Childhood externalizing disorders tripled risk of early-onset high cannabis problems (RR=2.82)
What the researchers found
Five trajectories identified: stable-no problems (85%), early-onset high (2%), late-onset high (3%), early-onset low (6%), late-onset low (5%). Externalizing disorders at age 10 predicted three of four problem trajectories. Internalizing disorders were only associated with late-onset low problems (protective: RR=0.50). Short-term memory at age 8 was associated with late-onset high problems (RR=1.09).
Why it matters
This study identifies a modifiable target for preventing problematic cannabis use: childhood externalizing disorders (conduct problems, ADHD-type behavior). Intervening on these behaviors at age 10 could potentially prevent cannabis problems starting at age 15.
The numbers in context
6,049 participants; 85% no problems; externalizing disorders: RR=2.82 (early-high), 1.62 (late-high), 1.82 (early-low); internalizing: RR=0.50 (late-low only); memory: RR=1.09 (late-high only).
How the study worked
Analysis within ALSPAC UK birth cohort. 6,049 participants with cannabis problem data (CAST) at 2+ timepoints between ages 15-24. Risk factors: internalizing and externalizing disorders at age 10, cognitive function at age 8. Longitudinal latent class analysis.
What this study cannot tell us
59% female sample may affect generalizability. ALSPAC cohort is predominantly white (95.7%). Cannabis problems assessed by screening tool, not clinical diagnosis. Attrition from birth cohort may bias results.
How to read the evidence
Prospective birth cohort with childhood risk factors measured years before cannabis use onset provides strong temporal evidence.
When this study was published
2025 analysis of the ALSPAC UK birth cohort spanning childhood to young adulthood.
The bigger picture
The finding that externalizing but not internalizing disorders predict cannabis problems is clinically important. It suggests prevention efforts should focus on children with behavioral problems rather than anxious/depressed children, who may actually be at lower risk for some problem patterns.
Questions still open
- Would treating childhood externalizing disorders reduce later cannabis problems?
- Why were internalizing disorders protective for late-onset low problems?
Common questions
Can you predict who will have cannabis problems?
Do anxious children have more cannabis problems?
Read the original research
Association of childhood mental health and cognition with longitudinal patterns of cannabis problems in adolescence.
Psychological medicine, 55, e129
Citation
Lees Thorne, Rachel; Hines, Lindsey A; Burke, Chloe; Jones, Hannah J; Freeman, Tom P. (2025). Association of childhood mental health and cognition with longitudinal patterns of cannabis problems in adolescence.. Psychological medicine, 55, e129. https://doi.org/10.1017/S0033291725001175
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