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Drugs Context. 2018 Sep 17;7:212541. doi: 10.7573/dic.212541. eCollection 2018.

Exploring the association of legalisation status of cannabis with problematic cannabis use and impulsivity in the USA.

Author information

Brain & Mental Health Laboratory, Monash Institute of Cognitive & Clinical Neuroscience, and School of Psychological Sciences, Monash University, Melbourne, Victoria, Australia.
Cognitive Neuroscience Unit, School of Psychology, Deakin University, Geelong, Victoria, Australia.
School of Psychology and Illawarra Health and Medical Research Institute, University of Wollongong, New South Wales, Australia.



There has been an increased trend towards the legalisation of medicinal and recreational cannabis use worldwide. This has been controversial as the long-term effects of frequent cannabis use on the brain are still poorly understood.


In this study, we investigated whether the legal status of cannabis in the United States of America (USA) is associated with problematic cannabis use and impulsivity in 329 frequent cannabis users. The data were collected in 2015 and were analysed in 2017. Ethical approval for this study was obtained from Monash University in 2015.


The results indicated that participants' problematic cannabis use and impulsivity was not different whether they resided in states where cannabis is legal for medical and/or recreational use or prohibited.


The present study is a cross-sectional design, making it difficult to infer causality and establish whether cannabis use is a cause, consequence, or correlate of altered impulsivity.


Our study supports the notion that frequent cannabis use is associated with impulsive behaviours, whilst, conversely, we did not find an association between US state legalisation and problematic cannabis use or impulsivity.


impulsivity; legal status of cannabis in the USA; problematic cannabis use

Conflict of interest statement

Disclosure and potential conflicts of interest: Murat Yücel received funds from David W Turner Endowment Fund and Adrian Carter received grants from the National Health and Medical Research Council during the conduct of the study. The International Committee of Medical Journal Editors (ICMJE) Potential Conflicts of Interests form for the authors are available for download at

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