Diverging trends in alcohol use and mental health in Australian adolescents: A cross-cohort comparison of trends in co-occurrence.

Background: In recent years, psychological distress in Western countries has rapidly increased among older adolescents while alcohol use has declined, though little is known about younger adolescents. It is also unclear if and how these trends relate to co-occurring alcohol use and distress. This study sought to examine temporal changes in the prevalence of distress, alcohol use, and their co-occurrence among young Australians. Methods: This study used data from 13,388 youth in their early teens (aged 12-14). Differences in the prevalence of high psychological distress (Kessler-6 ≥ 13), any alcohol use (standard drink in past 3/6 months), and their co-occurrence across cohorts (2007, 2012, 2014, 2019) were tested through log-binomial regression models. Changes in co-occurrence across cohorts were tested with cohort-by-alcohol interactions predicting distress, and vice-versa. Differential trends by sex were evaluated. Results: From 2007 to 2019, the prevalence of high distress more than doubled (4.6%-13.5%) while alcohol use decreased by ∼90% (11.8%-3.1%). Distress increased more-so among females, while alcohol use decreased more-so among males. The prevalence of high distress was significantly greater among adolescents who used alcohol compared to those who had not (>2 times higher), with this co-occurrence remaining consistent across cohorts. Conclusions: Psychological distress appears to be increasing similarly among youth in their early teens who do and do not use alcohol. At the same time, alcohol use is decreasing similarly among youth with and without distress. While alcohol use does not appear to be a driver of increases in distress, rates of co-occurring alcohol use and distress remain high. Addressing co-occurrence and distress-specific mechanisms remain necessary.