Factors Associated With Cocaine Use at 17 and 20 Years Old: A Longitudinal Analysis of a Nationally Representative Cohort

Margaret M Brennan; Massimo Cavallaro; Deirdre Mongan; Anne Doyle; Seán R Millar; Lina Zgaga; Bobby P Smyth; Elizabeth Nixon; Jo-Hanna Ivers; Brian Galvin; Cathal Walsh; Cathal McCrory; Noel D McCarthy

doi:10.1016/j.jadohealth.2024.10.033

Factors Associated With Cocaine Use at 17 and 20 Years Old: A Longitudinal Analysis of a Nationally Representative Cohort

J Adolesc Health. 2025 Jan 16:S1054-139X(24)00551-2. doi: 10.1016/j.jadohealth.2024.10.033. Online ahead of print.

Authors

Affiliations

¹ Department of Public Health & Primary Care, Institute of Population Health, School of Medicine, Trinity College Dublin, Dublin, Ireland. Electronic address: brennm32@tcd.ie.
² The Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research, School of Life Sciences and Mathematics Institute, University of Warwick, Coventry, United Kingdom; School of Computing and Mathematical Sciences, University of Leicester, Leicester, United Kingdom.
³ National Drugs & Alcohol Strategies, Health Research Board, Dublin, Ireland.
⁴ National Drugs & Alcohol Strategies, Health Research Board, Dublin, Ireland; School of Public Health, University College Cork, Cork, Ireland.
⁵ Department of Public Health & Primary Care, Institute of Population Health, School of Medicine, Trinity College Dublin, Dublin, Ireland.
⁶ Department of Public Health & Primary Care, Institute of Population Health, School of Medicine, Trinity College Dublin, Dublin, Ireland; Adolescent Addiction Service, Bridge House, Cherry Orchard Hospital, Dublin, Ireland.
⁷ School of Psychology, Trinity College Dublin, Dublin, Ireland.
⁸ The Irish Longitudinal Study on Ageing (TILDA), Department of Medical Gerontology, School of Medicine, Trinity College Dublin, Dublin, Ireland.

PMID: 39818654
DOI: 10.1016/j.jadohealth.2024.10.033

Abstract

Purpose: Despite growing concerns about trends in cocaine use, there is a shortage of longitudinal research that prospectively examines risk and protective factors associated with cocaine initiation and use in general youth populations. This study addresses this gap.

Methods: Growing Up in Ireland is a nationally representative cohort. Individual, family, and socio-environmental exposures associated with incident past-year cocaine use at ages 17 (N = 5965) and 20 (n = 4549) were assessed with survey-weighted logistic regression using generalised estimating equations. Prevalent past-year cocaine use at 20 (N = 4679) was analysed using generalised estimating equations complemented by gradient-boosted decision trees and Shapley explanations.

Results: 221 (3.7%) self-reported cocaine use at 17 and 1072 (22.9%) at 20. Alcohol use at 14 or younger was associated with eight times the odds of cocaine use at 17 (aOR 8.0, 95% CI 1.7-37.3) and 19 times at 20 (aOR 19.2, 95% CI 8.6-43.2). Peer cannabis use was associated with 7 times the odds of cocaine use at 17 (aOR 7.3, 95% CI 2.9-18.3) and double at 20 (aOR 2.4, 95% CI 1.8-3.2). Growing up in a neighbourhood where substance use was common doubled the odds of cocaine use at 17 (aOR 2.4, 95% CI 1.3-4.4). Shapley explanations revealed individual-specific positive or negative impacts of exposures.

Discussion: Cocaine use among 20-year-olds in Ireland is higher than reported internationally, and increases sharply between the ages of 17 and 20, suggesting a need for interventions targeting this age group. However, associations with early adolescent factors suggest that early interventions may also be important.

Keywords: Adolescent; Cocaine; Young adult.