Cannabis dependence
Cannabis dependence or cannabis use disorder is defined in the fifth revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) as a condition requiring treatment.
Cannabis is one of the most widely used drugs in the world, although physical addiction has not been proven with a dependence rate of about 9% in adult users. In the US, as of 2013, cannabis is the most commonly identified illicit substance used by people admitted to treatment facilities. Demand for treatment for cannabis use disorder increased internationally between 1995 and 2002.
Contents
Characteristics
There is a high prevalence of cannabis use in the US. Among individuals who have ever used cannabis, 9% develop dependence, and 10-20% of those who use cannabis daily develop dependence. Cannabis use is associated with comorbid mental health problems, such as mood and anxiety disorders, and discontinuing cannabis use is difficult for some users.
Signs and symptoms
Although not medically serious, cannabis withdrawal symptoms can occur in one half of patients in treatment for cannabis use disorders. These symptoms include dysphoric mood (anxiety, irritability, depressed mood, restlessness), disturbed sleep, gastrointestinal symptoms, and decreased appetite. Most symptoms begin during the first week of abstinence and resolve after a few weeks.
Risk factors
Dependence on cannabis is more common among heavy users. Marijuana use can lead to increased tolerance and, in some users, withdrawal symptoms when trying to stop. Prolonged marijuana use produces both pharmacokinetic changes (how the drug is absorbed, distributed, metabolized, and excreted) and pharmacodynamic changes (how the drug interacts with target cells) to the body. These changes require the user to consume higher doses of the drug to achieve a common desirable effect (known as a higher tolerance), and reinforce the body's metabolic systems for synthesizing and eliminating the drug more efficiently.
Cannabis users can develop tolerance to the effects of THC. Tolerance to the behavioral and psychological effects of THC has been demonstrated in adolescent humans and animals.The mechanisms that create this tolerance to THC are thought to involve changes in cannabinoid receptor function.
Certain factors are considered to heighten the risk of developing cannabis dependence and longitudinal studies over a number of years have enabled researchers to track aspects of social and psychological development concurrently with cannabis use. Increasing evidence is being shown for the elevation of associated problems by the frequency and age at which cannabis is used, with young and frequent users being at most risk.
The main factors in Australia related to a heightened risk for developing problems with cannabis use include frequent use at a young age; personal maladjustment; emotional distress; poor parenting; school drop-out; affiliation with drug-using peers; moving away from home at an early age; daily cigarette smoking; and ready access to cannabis. The researchers conclude there is emerging evidence that positive experiences to early cannabis use are a significant predictor of late dependence and that genetic predisposition plays a role in the development of problematic use.
High risk groups
A number of groups have been identified as being at greater risk of developing cannabis dependence and include adolescent populations, Aboriginal and Torres Strait Islanders (in Australia) and people suffering from mental health conditions.
Adolescents
Young people are at greater risk of developing cannabis dependency because of the association between early initiation into substance use and subsequent problems such as dependence, and the risks associated with using cannabis at a developmentally vulnerable age. In addition there is evidence that cannabis use during adolescence, at a time when the brain is still developing, may have deleterious effects on neural development and later cognitive functioning.
Although rates of adolescent substance use have typically been higher among boys than girls (Bachman et al., 1991; SAMHSA, 2007), empirical work points to a narrowing and/or closing of this gender gap where girls may actually be catching up or surpassing their male peers in terms of substance use rates (Donnermeyer, 1992; Johnston, O'Malley, Bachman, Schulenberg, 2006; Wallace et al., 2003). This pattern has been displayed among samples of youth from across a variety of racial and ethnic categories. Recent findings from the Monitoring the Future (MTF) project suggest that although male substance use tends to be greater than that of females at 12th grade, gender differences in earlier years (around 8th grade) are minimal, with some annual drug use rates higher for females than males (Johnston, O'Malley, Bachman, «fe Schulenberg, 2006).
Aboriginal and Torres Strait Islanders
Cannabis usage is part of a broader picture of poor health and well-being, stemming from the alienation and dispossession experienced by this population over time.Many of the social determinants of harmful substance use are disproportionately present in Aboriginal and Torres Strait Islander communities.
Psychiatric disorders
McLaren and Mattick show a correlation between populations who suffer from a mental disorder such as schizophrenia and a worsening of these symptoms with cannabis use. This correlation could partially be a matter of self-medication. Cannabidiol (CBD) is a cannabinoid present in varying concentrations in most strains of cannabis. CBD is known to safely treat psychosis.
Diagnosis
Cannabis use Disorder is recognized in the fifth version of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), which added Cannabis withdrawal as a new condition.
Treatment
No medications have been found effective for cannabis dependence as of 2014, but psychotherapeutic models hold promise.
The most commonly accessed forms of treatment in Australia are 12-step programmes, physicians, rehabilitation programmes, and detox services, with inpatient and outpatient services equally accessed. In the EU approximately 20% of all primary admissions and 29% of all new drug clients in 2005, had primary cannabis problems. And in all countries that reported data between 1999-2005 the number of people seeking treatment for cannabis use increased.
Treatment options for cannabis dependence are far fewer than for opiate or alcohol dependence. Most treatment falls into the categories of psychological or psychotherapeutic, intervention, pharmacological intervention or treatment through peer support and environmental approaches. Screening and brief intervention sessions can be given in a variety of settings, particularly at doctor's surgeries, which is of importance as most cannabis users seeking help will do so from their general practitioner rather than a drug treatment service agency.
Clinicians differentiate between casual users who have difficulty with drug screens, and daily heavy users, to a chronic user who uses multiple times a day. The sedating and anxiolytic properties of THC in some users might make the use of cannabis an attempt to self-medicate personality or psychiatric disorders.
Psychological
Psychological intervention includes cognitive behavioral therapy (CBT), motivational enhancement therapy (MET), contingency management (CM), supportive-expressive psychotherapy (SEP), family and systems interventions, and twelve-step programs.
Evaluations of Marijuana Anonymous programs, modelled on the 12-step lines of Alcoholics Anonymous and Narcotics Anonymous, have shown small beneficial effects for general drug use reduction.[medical citation needed] In 2006, the Wisconsin Initiative to Promote Healthy Lifestyles implemented a program that helps primary care physicians identify and address marijuana use problems in patients.
Pharmacological
As of 2012, there is no medication that has been proven effective for treating cannabis use disorder; research is focused on three treatment approaches: agonist substitution, antagonist, and modulation of other neurotransmitter systems. Dronabinol is an agonist that is legally available; in some cases and trials, it reduced symptoms of withdrawal and reduced cannabis use. Entacapone was well-tolerated and decreased cannabis cravings in a trial on a small number of patients. Acetylcysteine (NAC) decreased cannabis use and craving in a trial. Atomoxetine in a small study showed no significant change in cannabis use, and most patients experienced adverse events. Buspirone shows promise as a treatment for dependence; trials show it reducing cravings, irritability and depression. Divalproex in a small study was poorly tolerated and did not show a significant reduction in cannabis use among subjects.
Barriers to treatment
Research that looks at barriers to cannabis treatment frequently cites a lack of interest in treatment, lack of motivation and knowledge of treatment facilities, an overall lack of facilities, costs associated with treatment, difficulty meeting program eligibility criteria and transport difficulties. A technical report compiled by Australia's National Cannabis Centre.
Epidemiology
Cannabis is the most common illegal drug worldwide. It is responsible for most illicit drug admissions in the US.
In the US, 10 to 20% of consumers who use cannabis daily become dependent.
Research
Columbia University, in collaboration with the National Institute on Drug Abuse (NIDA), is undertaking a clinical trial that looks at the effects of combined pharmacotherapy on cannabis dependency, to see if Lofexidine in combination with Marinol is superior to placebo in achieving abstinence, reducing cannabis use and reducing withdrawal in cannabis-dependent patients seeking treatment for their marijuana use. Men and women between the ages of 18-60 who met DSM-IV criteria for current marijuana dependence were enrolled in a 12-week trial that started in January 2010.
See also
La Guardia Committee, the first in depth study into the effects of cannabis.
