Australian Research Council, Australian Rotary Health, Foundation for Alcohol Research and Education, National Drug and Alcohol Research Centre.

The Australian Parental Supply of Alcohol Longitudinal Study (APSALS) was established in 2010 to investigate the short- and long-term associations between exposure to early parental alcohol provision, early adolescent alcohol initiation, subsequent alcohol use and alcohol-related harms, controlling for a wide range of parental, child, familial, peer and contextual covariates. The cohort commenced with 1927 parent-child dyads comprising Australian Grade 7 school students (mean age = 12.9 years, range = 10.8-15.7 years), and a parent/guardian. Baseline, 1- and 2-year follow-up data have been collected, with > 90% retention, and a 3-year follow-up is under way. The data collected include child, familial, parental and peer factors addressing demographics, alcohol use and supply, parenting practices, other substance use, adolescent behaviours and peer influences. The cohort is ideal for prospectively examining predictors of initiation and progression of alcohol use, which increases markedly through adolescence.

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.

Initiating alcohol use earlier in adolescence is associated with an increased risk of binge drinking and higher quantity of consumption in late secondary school, supporting an argument for delaying alcohol initiation for as long as possible to reduce the risk for problematic use in later adolescence and the alcohol-related harms that may accompany this use.