Onset of opportunity to use cannabis and progression from opportunity to dependence: Are influences consistent across transitions?

Ms Lindsey Hines

Based at the National Addiction Centre, King's College London, Lindsey is a final year PhD student. Her current research uses epidemiological and behavioural genetic analyses to determine the relationship between speed of early transitions in substance use (focusing on cannabis and heroin) and later drug use outcomes. The project also identifies genetic and environmental influences on these transitions.

Lindsey previously worked as a research assistant on the PRAISe trial testing Contingency Management in opiate users, and in the King’s Centre for Military Health Research conducting analyses of mental health in the UK military.

Background: Little is known about factors which influence earlier opportunity to use drugs, or whether these factors overlap with those associated with dependence.

Aims: Identify factors associated with 1) earlier opportunity to use cannabis and 2) progression to cannabis dependence. 

Design: Cross-sectional study

Setting: Australia

Participants: 3824 twins and siblings

Measurements: Age of onset of cannabis use opportunity and age of onset of DSM-IV cannabis dependence.  

Analyses: Survival analyses identified factors associated with hazard of earlier cannabis use opportunity and progression to cannabis dependence. 

Findings: Factors associated with increased risks of both opportunity to use cannabis and cannabis dependence were conduct disorder (opportunity HR 1.26, 95%CI 1.05  -  1.51; dependence HR 2.25, 95%CI 1.70  -  2.97), parental drug problems (opportunity HR 9.28, 95%CI 2.18-39.47; dependence HR 3.59, 95%CI 1.79-7.20), childhood sexual abuse (HR 1.16, 95%CI 1.03-1.32), and weekly tobacco use (opportunity HR 1.90, 95%CI 1.71-2.10; dependence HR 3.36, 95%CI 2.56-4.42). Frequent childhood religious attendance (HR 0.55, 95%CI 0.36-0.84) and monthly alcohol use (HR 1.73, 95%CI 1.57-1.89) were uniquely associated with transition to opportunity. Gender (HR 0.40, 95%CI 0.27  -  0.59), depressive episode (HR 1.32, 95%CI 1.03-1.69), tobacco dependence (HR 1.38, 95%CI 1.05-1.81), other illegal drug use (HR 2.16, 95% CI 1.68-2.77), and other illegal drug dependence (HR 2.30, 95% CI 1.91-2.76) were uniquely associated with progression to dependence.

Conclusion: The profile of opportunity to use and dependence correlates only partially overlaps, with evidence for unique contributions. The targeting and content of interventions may benefit from being tailored to the stages of drug use.

POSTER November 2015

Co-Authors

Lindsey A. Hines1, Katherine I. Morley1, John Strang1, Arpana Agrawal2, Elliot C. Nelson2, Dixie Statham3, Nicholas G. Martin4 and Michael T. Lynskey1 1 Addictions Department, Institute of Psychiatry, Psychology and Neuroscience, ; Kings College London, London, England 2 Department of Psychiatry, Washington University School of Medicine, St Louis, MO, USA 3 School of Social Sciences, University of the Sunshine Coast, Queensland, Australia 4 QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia

Conflicts of interest:

MRC/IoPPN Studentship. No declarations of interest from any authors.


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