In a 30-year French cohort, 16% of cannabis users maintained persistent use from adolescence to their mid-40s, with early cannabis initiation, male sex, academic difficulties, and childhood family conflict as key predictors.
School counselors, family therapists, substance use prevention specialists, and researchers studying long-term cannabis use patterns.
What the researchers found
Three cannabis trajectories were identified: declining (69.9%), fluctuating (13.7%), and persistent (16.4%). Persistent use was predicted by male sex (OR 3.66), academic difficulties (OR 2.47), and early initiation of cannabis (OR 2.31) or combined tobacco+cannabis (OR 3.07). Fluctuating use was predicted by parental smoking (OR 2.18) and parental conflict/stress before age 17 (OR 1.93).
Why it matters
Understanding that one in six cannabis users maintains persistent use into their mid-40s — and that this pattern is predictable from childhood factors — creates opportunities for early identification and targeted prevention before patterns become entrenched.
The numbers in context
622 participants, 14 measurements over 22 years (1999–2021). Declining: 69.9%. Fluctuating: 13.7%. Persistent: 16.4%. Male sex: OR 3.66 for persistent. Academic difficulties: OR 2.47. Early cannabis + tobacco initiation: OR 3.07. Parental conflict before 17: OR 1.93 for fluctuating.
How the study worked
Group-Based Trajectory Modelling of 622 participants from the French TEMPO cohort with 14 measurement points of cannabis use from 1999 to 2021 (ages 15–46). Multinomial logistic regression examined associations with early individual and family factors.
What this study cannot tell us
French cohort — patterns may differ in other countries, especially those with different legalization timelines. Self-reported use across 14 waves — some recall bias. Cannot account for all confounders. TEMPO cohort participants are children of a larger epidemiological study, potentially limiting representativeness.
How to read the evidence
30-year longitudinal cohort with 14 measurement points and sophisticated trajectory modeling, providing strong evidence for long-term use patterns.
When this study was published
Published 2025, data from 1999–2021.
The bigger picture
Most people who use cannabis in adolescence will naturally decrease their use over time (70%). But the 16% with persistent use into middle age represent a group that may need sustained support, and their risk factors are identifiable in childhood — before cannabis use even begins.
Questions still open
- Would early interventions targeting academic support and family conflict reduce persistent cannabis use decades later? Do persistent users face different health outcomes than declining users? How does legalization affect these trajectories?
Common questions
Do most people who try cannabis as teens keep using it?
Can you predict who will become a lifelong user?
Read the original research
Childhood events as factors in continued cannabis use in adulthood: a longitudinal study of a 30-year follow-up cohort.
Journal of cannabis research, 7(1), 89
Citation
Wallez, Solène; Eren, Filiz; Kousignian, Isabelle; Avenin, Guillaume; Melchior, Maria; Mary-Krause, Murielle. (2025). Childhood events as factors in continued cannabis use in adulthood: a longitudinal study of a 30-year follow-up cohort.. Journal of cannabis research, 7(1), 89. https://doi.org/10.1186/s42238-025-00345-0
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