On the 10 year anniversary of proposition 216, California’s Compassionate Use Act, which essentially legalized marijuana use with a prescription by a physician (“medical marijuana”) and two years after Colorado passed Amendment 64 (which legalized marijuana use in Colorado without any requirement for a prescription) it seems timely to review what we know about the mental health effects of marijuana use and marijuana use disorder.
12.5% of persons age 18 or older in the United States reported past-year use of cannabis in 2013 and this is about 19% higher than the 10.5% found in 2002. This increase is probably related to the fact that there is an inverse relationship between cannabis use and the perception of harmfulness: as cannabis use becomes normalized in society people may be more likely to use it.
The study we summarize is based on an analysis of the data from the National Epidemiologic Survey on Alcohol and Related Conditions – III (NESARC-III), a nationally representative survey of 46,500 adult Americans that collected data on alcohol use disorders and their associated disabilities and was funded by the National Institute for Health (NIH).
Using this data, Hasin and colleagues conducted a rigorous analysis of the prevalence, demographic characteristics, psychiatric comorbidity, disability, and treatment for DSM-5 cannabis use disorders in the U.S. adult population.
DSM-5 changed the substance use criteria. It dropped the criteria for legal problems and eliminated the distinction between substance abuse and substance dependence, instead creating a continuum of severity from mild substance use disorder to severe substance use disorder. As a result, it is easier to see the relationship between the severity of substance use and other problems.
In editorial accompanying the article, Wilson M. Compton, M.D., M.P.E. and Ruben Baler, Ph.D. write that –
Cannabis use disorder was found to be prevalent, with a past-year rate of 2.5% and a lifetime rate of 6.3%. Rates were higher among men, Native Americans, unmarried persons, younger persons, and those with low incomes. Comorbidity was found to be common, with strong associations of cannabis use disorder with other substance use disorders, affective disorders, anxiety disorders, and personality disorders… Hasin and colleagues found that increasing DSM-5 cannabis use disorder severity was also associated with poorer functioning and stronger correlation with risk factors.
A summary of the information from this article is contained in the video below.
Pacula R, Jacobson M, Maksabedian EJ: In the weeds: a baseline view of cannabis use among legalizing states and their neighbours. Addiction (Epub ahead of print, Dec 21, 2015)
Grucza RA, Agrawal A, Krauss MJ, et al: Recent trends in the prevalence of marijuana use and associated disorders in the United States. JAMA Psychiatry 2016; 73:300–301
Blanco C, Hasin DS, Wall MM, et al: Cannabis use and risk of psychiatric disorders: prospective evidence from a US national longitudinal study. JAMA Psychiatry (Epub ahead of print, Feb 17, 2016)
Volkow ND, Baler RD, Compton WM, et al: Adverse health effects of marijuana use. N Engl J Med 2014; 370:2219–2227
Hasin DS, Kerridge BT, Saha TD, et al: Prevalence and correlates of DSM-5 cannabis use disorder, 2012–2013: findings from the National Epidemiologic Survey on Alcohol and Related Conditions–III. Am J Psychiatry 2016; 173:588–599
Compton WM, Thomas YF, Conway KP, et al: Developments in the epidemiology of drug use and drug use disorders. Am J Psychiatry 2005; 162:1494–1502
Hasin DS, O’Brien CP, Auriacombe M, et al: DSM-5 criteria for substance use disorders: recommendations and rationale. Am J Psychiatry 2013; 170:834–851
Batalla A, Bhattacharyya S, Yücel M, et al: Structural and functional imaging studies in chronic cannabis users: a systematic review of adolescent and adult findings. PLoS One 2013; 8:e55821
Filbey F, Yezhuvath U: Functional connectivity in inhibitory control networks and severity of cannabis use disorder. Am J Drug Alcohol Abuse 2013; 39:382–391
Zalesky A, Solowij N, Yücel M, et al: Effect of long-term cannabis use on axonal fibre connectivity. Brain 2012; 135:2245–2255