Supplementary Material for: Longitudinal Assessment of Alcohol Consumption throughout the First COVID-19 Lockdown: Contribution of Age and Pre-Pandemic Drinking Patterns

Introduction: The COVID-19 outbreak and the related lockdown measures have raised concerns regarding mental health, including alcohol misuse. Preliminary studies investigated alcohol consumption at the early stages of lockdown, but no longitudinal data regarding its evolution during and after the first lockdown are currently available. Methods: We investigated changes in alcohol consumption among a convenience sample of 1,693 French-speaking Belgian adults using a 3-stage longitudinal online survey. All participants reported their consumption at different stages of lockdown: before lockdown onset (retrospectively, T0), at 2 different times during lockdown (T1 and T2), and after lockdown offset (T3). We also measured socio-demographic variables and the harmfulness of drinking patterns before lockdown. Results: A mixed model with negative binomial distribution indicated that participants decreased their alcohol consumption after lockdown onset and returned to their initial alcohol consumption after lockdown offset. Younger individuals (18–30 years old) were more likely to decrease their consumption during the lockdown period (T1 and T2) than the periods preceding or following lockdown (T0 and T3), especially if they presented hazardous or problematic drinking patterns before lockdown. We only observed a rebound effect after lockdown offset among young moderate drinkers. All participants kept stable their alcohol consumption during lockdown (T1 and T2). Conclusions: Lockdown onset and offset constitute key periods for alcohol consumption changes during the COVID-19 crisis, particularly in youth and in individuals with hazardous or problematic drinking patterns.