# Childhood events as factors in continued cannabis use in adulthood: a longitudinal study of a 30-year follow-up cohort

## TL;DR

This study shows that childhood and family factors influence whether cannabis use continues into adulthood, with some patterns linked to male gender and early exposure.

## Contribution

The study identifies distinct cannabis use trajectories and their early-life predictors over a 30-year period.

## Key findings

- Three cannabis use trajectories were identified: declining, fluctuating, and persistent.
- Fluctuating use was linked to male gender, parental smoking, and childhood stress.
- Persistent use was associated with being male, academic difficulties, and early cannabis initiation.

## Abstract

Cannabis use patterns have evolved over time, with increasing persistence into adulthood. This study aims to identify cannabis use trajectories from adolescence to adulthood and to examine the influence of early individual and family factors on these trajectories.

This study included 622 participants from the French TEMPO cohort who reported cannabis use between 1999 and 2021, based on 14 measurements points. Cannabis consumption from adolescence to adulthood (ages 15 to 46) was assessed using Group-Based Trajectory Modelling (GBTM). Associations with early individual and family factors were examined using multinomial logistic regression.

We identified three distinct cannabis use trajectories: declining consumption (69.9%), fluctuating consumption (13.7%), characterized by an initial increase followed by a decrease, and persistent consumption (16.4%). The fluctuating use trajectory was associated with being male (OR = 2.15, 95%CI = 1.31–3.54), having parents who smoked (OR = 2.18 95%CI = 1.18–4.02), and experiencing parental conflict, stress, or frequent absence before age 17 (OR = 1.93, 95%CI = 1.15–3.23). The persistent use trajectory was associated with being male (OR = 3.66, 95%CI = 2.19–6.09), academic difficulties (OR = 2.47, 95%CI = 1.45–4.22), and early initiation of cannabis (OR = 2.31, 5%CI = 1.11–4.79) or both tobacco and cannabis (OR = 3.07, 95%CI = 1.57–6.02).

These findings underscore the importance of early prevention and intervention strategies, particularly in populations where cannabis use persists despite legal restrictions. Given the potential health and social consequences of prolonged cannabis use, it is essential to identify early-life risk factors to inform targeted policy measures aimed at reducing consumption and preventing cannabis use disorders.

The online version contains supplementary material available at 10.1186/s42238-025-00345-0.