Background

In 2023, the Health Research Board (HRB) partnered with Trinity College Dublin to examine the alcohol- and drug-related data collected in the nationally representative, longitudinal Growing Up in Ireland (GUI) study. A series of publications have ensued as a result of this collaboration.1-4 The most recent of these examined the association between age of alcohol initiation and hazardous alcohol use during adolescence with alcohol, tobacco, cannabis, and other drug use during early adulthood.5

Adverse childhood experiences (ACEs) describe different types of stressful or traumatic experiences during childhood, and exposure to extreme stress during critical periods of early life may increase the likelihood of exposure to a range of adverse factors.1 Importantly, studies have demonstrated positive associations between ACEs and substance use behaviours in young adults.2 However, many of these are based on cross-sectional data, which cannot provide evidence on the hypothesised direction of association between ACEs and substance use. In addition, the pathway between ACEs and substance misuse among emerging adults is not fully understood and few studies have investigated potential mediating factors. 

The Republic of Ireland ranks fourth globally for past-year cocaine use, with 2.4% of the general adult population reporting such use in 2019.1 It ranks second in Europe for lifetime cocaine use among 15–24-year-olds, with such use estimated at 6.8% in 2021.2 National drug treatment surveillance data revealed a 259% increase in cases where cocaine was the main problem drug between 2016 and 2022; in 2022, cocaine surpassed opioids as the leading problem drug, accounting for 34% of all drug treatment cases.3 In addition, among individuals aged 15–24 years, cocaine-related hospital discharges rose by 83% between 2015 and 2019, while cocaine-related deaths increased by 41% between 2007 and 2017.2 However, despite growing concerns about trends in cocaine use in Ireland, there is a lack of longitudinal studies that prospectively examine factors associated with cocaine initiation and use in general youth populations. 

Problem drug use (PDU) is defined as recurrent drug use that is causing harm to an individual, or is placing them at a high probability or risk of suffering harm.1 Substances associated with PDU include opioids, cocaine (powder and crack), amphetamines, benzodiazepines, Z-drugs, and gabapentinoids. PDU can lead to many harms for populations and individuals. Such harms include increased criminal activity, drug-related litter, increased risk of infectious diseases passed on from shared syringes and needles, substance use disorders, overdoses, and death.