Age differences in the behavioural economics of cannabis use: Do adolescents and adults differ on demand for cannabis and discounting of future reward?

A. Borissova, S. Soni, E. R. Aston, R. Lees, K. Petrilli, M. B. Wall, M.A.P. Bloomfield, E. Mertzani, A. Paksina, T. P. Freeman, C. Mokrysz, W. Lawn, H. V. Curran

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Abstract

Background: Adolescence is a period of psychological and neural development in which harms associated with cannabis use may be heightened. We hypothesised that adolescent who use cannabis (adolescentsWUC) would have steeper delay discounting (preference for immediate over future rewards) and greater demand (relative valuation) for cannabis than adults who use cannabis (adultsWUC). Methods: This cross-sectional study, part of the ‘CannTeen’ project, compared adultsWUC (n = 71, 26–29 years old) and adolescentsWUC (n = 76, 16–17 years old), and gender- and age-matched adolescent (n = 63) and adult (n = 64) controls. AdolescentsWUC and adultsWUC used cannabis 1–7 days/week and were matched on cannabis use frequency (4 days/week). The Monetary Choice Questionnaire assessed delay discounting. A modified Marijuana Purchase Task (MPT) assessed cannabis demand in adolescentsWUC and adultsWUC. The MPT yielded five indices: intensity (amount of cannabis used at zero cost), Omax (total peak expenditure), Pmax (price at peak expenditure), breakpoint (cost at which cannabis demand is suppressed to zero) and elasticity (degree to which cannabis use decreases with increasing price). Analyses were adjusted for covariates of gender, socioeconomic status, other illicit drug use. Results: Both adolescentsWUC and adultsWUC had steeper delay discounting than controls (F, (1,254)= 9.13, p = 0.003, ηp2= 0.04), with no significant age effect or interaction. AdolescentsWUC showed higher intensity (F, (1,138)= 9.76, p = 0.002, ηp2= 0.07) and lower elasticity (F, (1,138)= 15.25, p < 0.001, ηp2= 0.10) than adultsWUC. There were no significant differences in Pmax, Omax or breakpoint. Conclusion: Individuals who use cannabis prefer immediate rewards more than controls. AdolescentsWUC, compared to adultsWUC, may be in a high-risk category with diminished sensitivity to cannabis price increases and a greater consumption of cannabis when it is free.

Original languageEnglish
Article number109531
JournalDrug and Alcohol Dependence
Volume238
Early online date9 Jun 2022
DOIs
Publication statusPublished - 1 Sept 2022

Bibliographical note

Funding Information:
This work was supported by a grant from the Medical Research Council ( MRC ; award number MR/P012728/1 ) to HVC and TPF. AB is supported by a fellowship from the National Institute for Health Research (NIHR) UCLH Biomedical Research Centre and a NIHR Academic Clinical Fellowship. HVC is supported by grants from the MRC, United Kingdom (UK) Department of Health and by the National Institute for Health Research UCLH Biomedical Research Centre. MBW’s primary employer is Invicro LLC, a contract research organisation which performs commercial research for the pharmaceutical and biotechnology industries. MAPB is supported by grants from UK Research and Innovation, University College London, the British Medical Association Foundation for Medical Research, and the National Institute for Health University College London Hospitals Biomedical Research Centre. ERA is funded by NIGMS (National Institute of General Medical Sciences) COBRE grant P20GM130414 .

Keywords

  • Adolescent
  • Cannabis
  • Delay discounting
  • Marijuana purchase task

ASJC Scopus subject areas

  • Toxicology
  • Pharmacology
  • Psychiatry and Mental health
  • Pharmacology (medical)

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