OBJECTIVES: Adolescents often display heterogenous trajectories of alcohol use. Initiation and escalation of drinking may be important predictors of later harms, including alcohol use disorder (AUD). Previous conceptualizations of these trajectories lacked adjustment for known confounders of adolescent drinking, which we aimed to address by modeling dynamic changes in drinking throughout adolescence while adjusting for covariates.METHODS: Survey data from a longitudinal cohort of Australian adolescents (n = 1813) were used to model latent class alcohol use trajectories over 5 annual follow-ups (mean age = 13.9 until 17.8 years). Regression models were used to determine whether child, parent, and peer factors at baseline (mean age = 12.9 years) predicted trajectory membership and whether trajectories predicted self-reported symptoms of AUD at the final follow-up (mean age = 18.8 years). RESULTS:We identified 4 classes: abstaining (n = 352); late-onset moderate drinking (n = 503); early-onset moderate drinking (n = 663); and early-onset heavy drinking (n = 295). Having more alcohol-specific household rules reduced risk of early-onset heavy drinking compared with late-onset moderate drinking (relative risk ratio: 0.31; 99.5% confidence interval [CI]: 0.11-0.83), whereas having more substance-using peers increased this risk (relative risk ratio: 3.43; 99.5% CI: 2.10-5.62). Early-onset heavy drinking increased odds of meeting criteria for AUD in early adulthood (odds ratio: 7.68; 99.5% CI: 2.41-24.47). CONCLUSIONS:Our study provides evidence that parenting factors and peer influences in early adolescence should be considered to reduce risk of later alcohol-related harm. Early initiation and heavy alcohol use throughout adolescence are associated with increased risk of alcoholrelated harm compared with recommended maximum levels of consumption (late-onset, moderate drinking).WHAT'S KNOWN ON THIS SUBJECT: Adolescent drinking trajectories are often found to be heterogenous. Age at initiation and escalation of drinking may be important predictors of alcohol-related problems in early adulthood. However, no research has conceptualized these trajectories with adjustment for known confounders.WHAT THIS STUDY ADDS: Parenting factors (alcohol-specific household rules, child monitoring) in early adolescence predicted lower risk of early-onset heavy drinking, whereas peer influences increased risk. Early-onset heavy drinking increased the risk of meeting criteria for alcohol use disorder on the basis of self-reported symptoms.

Aims To estimate change in young people's alcohol consumption during COVID‐19 restrictions in Australia in early‐mid 2020, and test whether those changes were consistent by gender and level of consumption prior to the pandemic. Design Prospective longitudinal cohort Setting Secondary schools in New South Wales, Tasmania, and Western Australia. Participants Subsample of a cohort (n=443) recruited in the first year of secondary school in 2010‐11. Analysis data included three waves collected in Sep 2017 – July 2018, Sep 2018 ‐ May 2019 and Aug 2019 ‐ Jan 2020), and in May‐June 2020. Measurements The primary predictors were time, gender, and level of consumption prior to the pandemic. Outcome variables, analysed by mixed‐effects models, included frequency and typical quantity of alcohol consumption, binge drinking, peak consumption, alcohol‐related harm, and drinking contexts. Findings Overall consumption (frequency x quantity) during the restrictions declined by 17% (incidence rate ratio [IRR] 0.83; 95% confidence interval [CI] 0.73, 0.93), compared to February 2020, and there was a 34% decline in the rate of alcohol‐related harms in the same period (IRR 0.66; 95% CI 0.55, 0.80). Changes in alcohol consumption were largely consistent by gender. Conclusions From a survey of secondary school students in Australia, there is evidence for a reduction in overall consumption and related harms during the COVID‐19 restrictions.

Background and aims Adolescent drinking in Australia (and many other countries) has declined substantially since the early 2000s. This study aimed to test whether these declines have been maintained into adulthood and whether they are consistent across sub‐groups defined by sex and socio‐economic status. Design Quasi‐cohorts were constructed from seven repeated waves of cross‐sectional household survey data (2001–2019). Setting Australia. Participants A total of 20 733 respondents age between 14 and 24 (male: 9492; female: 11 241). Measurements Participants were grouped into five cohorts based on their birth year (from 1979–1983 to 1999–2003). Three measures of drinking were assessed: any past‐year consumption (yes/no), past‐year regular risky drinking (12 or more drinking episodes of >40 g of pure alcohol, yes/no) and total volume of alcohol consumed in the past year (in Australian standard drinks, 10 g of alcohol). Socio‐economic status was measured based on neighbourhood of residence. Findings Drinking declines were consistent across socio‐economic groups on all measures and trends were broadly similar for women and men. More recent birth cohorts had significantly lower levels of drinking across all three measures (odds ratios between 0.31 and 0.70 for drinking and risky drinking, coefficients between −0.28 and −0.80 for drinking volume). There were significant interactions between birth cohort and age for past‐year drinking and past‐year regular risky drinking, with cohort differences diminishing as age increased. Conclusions Lighter drinking adolescent cohorts appear to partly ‘catch up’ to previous cohorts by early adulthood, but maintain lower levels of drinking and risky drinking up to the age of 24. These ongoing reductions in drinking are spread evenly across socio‐economic groups.

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