Marijuana dependence

Marijuana is the most widely used illicit drug in the United States, and probably in the world. Although it is prohibited at the federal level in the United States, thirty-eight states, three territories, and Washington, DC, had approved its use for medical purposes, and twenty-four states, three territories, and Washington, DC, for recreational purposes by April 2023. Marijuana is hence becoming more widely available and socially sanctioned. Marijuana use can lead to cannabis use disorder, an addictive disorder in which the individual experiences clinically significant impairment or distress in relation to the use of marijuana. How the recently increased legal and social approval of marijuana use will affect rates of cannabis use disorder and its treatment are as yet unclear. Prevalence, risk factors, and behavioral and pharmacological treatments for cannabis use disorder are discussed.

Introduction

Marijuana is the leaves, stems, and seeds of the plant Cannabis sativa (including the subspecies Cannabis sativa indica and Cannabis sativa ruderalis). It is the most widely used illicit drug. In most cases, marijuana causes relatively brief and mild intoxication. The 2015 US National Survey on Drug Use and Health reported that, in 2022, about 61.9 million Americans ages twelve and older had used marijuana in the past year. According to the survey, about 19 million people in the United States met the criteria for a cannabis use disorder in 2022.

Cannabis use disorder can range from mild to severe. It is typically associated with dependence, which is distinct from addiction. Dependence occurs when stopping use of the drug would lead to withdrawal symptoms; addiction, according to the NIDA, occurs "when the person cannot stop using the drug even though it interferes with many aspects of his or her life." Chronic use of marijuana can affect motivational and reward systems, leading to addiction. For chronic users, ceasing marijuana use can result in cannabis use withdrawal, which can be similar to nicotine withdrawal in intensity and duration. Several treatments exist, including behavioral and pharmacological therapies.

Diagnosis

"Cannabis abuse" and "cannabis dependence" were initially listed as diagnoses in the third edition of the Diagnostic and Statistical Manual of Mental Disorders, or the DSM-III, published by the American Psychiatric Association (APA) in 1980. Before then, a diagnosis of drug addiction would have been made with a specification of marijuana as the drug. The DSM-III notes that at the time of publication, tolerance and withdrawal related to marijuana use had not been established, so cannabis dependence was to be diagnosed based on level of impairment rather than the presence of tolerance and withdrawal, as was the case for other drugs. The "abuse" and "dependence" diagnostic categories were carried through the DSM-IV with only minor changes. Although these terms are no longer in use, they and their related criterion were used as standards in research until the publication of the DSM-5 in 2013.

In the years since the DSM-III, scientists have established that tolerance and withdrawal do exist in cases of chronic marijuana use, and that these play a complex role in the addictive cycle. With the publication of the DSM-5, the diagnostic system changed to subsume both cannabis dependence and cannabis abuse into the category of "cannabis use disorder," where dependence and abuse are simply different points on the continuum of the disorder. (The same change was made for other substances for which dependence and abuse were previously considered distinct.) In addition to using marijuana in a way that results in clinically significant impairment or distress, the patient must meet at least two of eleven criteria to be considered dependent. Tolerance to the drug and a withdrawal syndrome upon stopping use of the drug are two of the listed criterion.

Acute Intoxication

Marijuana intoxication is usually relatively mild and short. It can include feelings of euphoria, levity, and relaxation. Marijuana intoxication is often accompanied by distorted perceptual experiences; for instance, the user may experience a distorted sense of time or distance. Users may experience a decreased sensation of pain, as marijuana alters the perception of pain. Negative effects may include paranoia, panic, drowsiness, and difficulty concentrating. When used for medical purposes, marijuana is most often used to decrease perception of pain, decrease nausea, and induce appetite.

Prevalence and Epidemiology

Cannabis use disorders have high prevalence rates, reflective of the widespread use of marijuana. According to the Substance Abuse and Mental Health Services Administration (SAMHSA), in 2022 about 61.9 million Americans ages 12 and up reported using marijuana in the past year. SAMHSA reported that in 2022, about 19 million Americans ages 12 and up who had used marijuana during the same time period, met the DSM-5 criteria for a cannabis use disorder, with 17.3 percent having a severe disorder. Rates of cannabis use disorders are higher in males and younger adults than in females and older adults. There are also differences in rates of cannabis use disorders between racial and ethnic groups in the United States.

Course of Addiction

Marijuana contains over sixty chemicals called cannabinoids, which are unique to the cannabis plant family. The cannabinoids found in marijuana are similar to the endogenous cannabinoid (or endocannabinoid) anandamide, which occurs naturally in the human brain that they can bind to existing cannabinoid receptors. The chemical responsible for marijuana's psychoactive effects is one of these cannabinoid compounds: delta-9-tetrahydrocannabinol, or ∆9-THC. Cannabinoid 1 receptors are found throughout the human brain, spinal cord, and peripheral nervous system, but it is in the brain that ∆9-THC's action at these receptor sites causes its psychoactive properties.

Marijuana is usually consumed by smoking in a small pipe or marijuana cigarette, or by vaporizing. When smoked, ∆9-THC quickly enters the bloodstream through the capillaries of the lungs and reaches the brain within seconds. Marijuana can also be eaten and the ∆9-THC absorbed into the blood stream through the gastrointestinal system. When eaten, the effects of marijuana are slower to commence and last longer. As users develop tolerance and require more of the drug to obtain effects, they may change their smoking methods by using paraphernalia (such as water pipes, also called bongs) that will cool the smoke so it can be held longer in the lungs, use pressurized devices to force smoke deeper into the lungs, or vaporize marijuana so that the smoke will not cause irritation that requires quick exhalation.

Most cannabis users start as adolescents or young adults. Most illicit drug users start with licit drugs, such as alcohol or tobacco, before trying marijuana or other illicit drugs; however, some follow an alternative sequence, trying marijuana first. Marijuana is often the first illicit drug tried because of its relative safety (as marijuana is not known to cause fatal overdose) and wide availability. Other risk factors for beginning marijuana use include peer influence, the presence of mental disorders (other than anxiety disorders), and one or more absent parents (due to death, divorce, or another reason). Risk factors for developing dependence include lower socioeconomic status, low self-esteem, and a parent who either has a mental disorder or died at an early age. It is unclear how these patterns will be affected by the legalization of marijuana for recreational and medical use.

Potential for addiction is dose-dependent, with higher doses and more frequent use leading to higher likelihood of addiction. Likewise, due to refined plant breeding and growing practices, marijuana is increasing in potency and is estimated to be 15 to 20 times stronger than it was in the 1960s. As ∆9-THC levels in marijuana has increased, the potential for addiction has risen, and the tolerance and withdrawal have become more prominent in maintaining cannabis use disorders.

Psychological Symptoms

Cannabis use can cause cognitive problems and loss of motivation for goal-directed activity. In the short term, marijuana use impairs cognitive and psychomotor performance, especially in relation to complex or demanding tasks. In some cases, reduced cognitive function can be found months after marijuana use is stopped; however, it is unclear in these cases if marijuana use caused the impairments or exacerbated existing cognitive problems. In cases of chronic use, antimotivational syndrome may occur, in which the individual seems depressed and lethargic and is unable to find motivation for daily activities that once seemed rewarding.

Physiological Symptoms

Because marijuana is usually smoked, the most significant consequence to physical health is respiratory problems. Known effects of cannabis smoke include increases in coughing, wheezing, and sputum production; the presence of chronic bronchitis symptoms; and inflammation or edema in the respiratory tract, as well as epithelial damage in the airway and bronchi.

Studies of the effect of regular marijuana use on lung function are complicated by the fact that many marijuana users also use tobacco, and therefore it is difficult to confidently attribute effects to either substance. However, a review of nineteen such studies, published in Primary Care Respiratory Journal in 2016, found that habitual marijuana smokers show no significant reduction in FEV₁/FVC ratio, which measures airflow obstruction (lower ratio indicates greater obstruction) and is consistently reduced in cigarette smokers. In fact, more recent studies suggest that chronic users may show an increase in both FEV₁ and FVC or in FVC alone, the latter of which may have contributed to previous observations of a reduced ratio. While studies also suggest that marijuana smokers are at increased risk of lung cancer, the evidence linking the two is not conclusive, again because most cannabis users who have since developed lung cancer also have a history of tobacco use.

Treatments

People who meet the criteria for cannabis use disorder also higher rates of alcohol use disorder and tobacco use disorder than the general population. Cannabis use can be seen as a secondary problem; however, it is likely an integral part of the picture for those who meet criteria for multiple diagnoses and requires treatment in its own right.

Cannabis use disorders are not easily treated. This is due in part to the fact that many with the disorder do not believe or have trouble accepting that they may be dependent on marijuana, or even that it is possible to be, as cannabis withdrawal symptoms are relatively mild compared to alcohol or to other illicit drugs, and the negative effects of its use tend to be less obvious. Research shows that most promising treatments are those already applied to other types of substance use disorders, such as motivational interviewing (MI) and cognitive behavior therapy (CBT). Relatively brief, immediate, and intense treatment has produced promising and durable outcomes; the SAMHSA guide on brief counseling for marijuana dependence recommends two sessions of motivational enhancement therapy (MET), an adaptation of MI, and nine further sessions incorporating MET and CBT, along with training in coping skills and case management.

One classic theory of drug addiction is that it is driven by negative reinforcement when the drug user suffers withdrawal symptoms, which are relieved by taking more of the drug. Several pharmacological interventions are under investigation for cannabis use disorders, some of which may alleviate this withdrawal so that further marijuana use is no longer negatively reinforced. Researchers have noted that administering synthetic ∆9-THC (dronabinol, trade name Marinol) will reduce symptoms of marijuana withdrawal. Other medications may be able to block the psychoactive effects of marijuana, such that further use is not rewarded. Although several medications are under investigation, none are as-yet approved for the treatment of cannabis use disorders.

Co-occurring Disorders

Marijuana users have higher rates of other mental disorders than are found in the general population, particularly mood disorders (including major depressive disorder and bipolar disorder), anxiety disorders (including panic disorders and social anxiety disorder), posttraumatic stress disorder, and personality disorders. Several studies in the 2010s and 2020s showed that people with a cannabis use disorder was two to four times more likely to experience psychosocial events, including depression and suicidal thoughts. In addition, cannabis use disorder was linked to a higher risk of developing schizophrenia. Cannabis users also have higher rates of other substance use disorders. These co-occurring diagnoses will need to be taken into account when planning treatment for individuals with cannabis use disorder.

Bibliography

“Cannabis (Marijuana).” National Institute on Drug Abuse, National Institutes of Health, Sept. 2024, nida.nih.gov/research-topics/cannabis-marijuana. Accessed 27 Nov. 2024.

Compton, Michael T., editor. Marijuana and Mental Health. American Psychiatric Association Publishing, 2016.

Diagnostic and Statistical Manual of Mental Disorders: DSM-5. 5th ed., American Psychiatric Association, 2013.

Highlights for the 2022 National Survey on Drug Use and Health. Substance Abuse and Mental Health Services Administration, 2022, www.samhsa.gov/data/sites/default/files/reports/rpt42731/2022-nsduh-main-highlights.pdf. Accessed 27 Nov. 2024.

Lyter, Sarah, reviewer. "Marijuana Use Is at an All-Time High—Here’s How It Affects Mental Health." Charlie Health, 18 June 2024, www.charliehealth.com/research/marijuana-mental-health-statistics. Accessed 27 Nov. 2024.

Panagis, George, et al. “Cannabinoid Regulation of Brain Reward Processing with an Emphasis on the Role of CB₁ Receptors: A Step Back into the Future.” Frontiers in Psychiatry, vol. 5, 2014, doi:10.3389/fpsyt.2014.00092. Accessed 27 Nov. 2024.

Preedy, Victor R., editor. Handbook of Cannabis and Related Pathologies: Biology, Pharmacology, Diagnosis, and Treatment. Elsevier, 2017.

Ribeiro, Luis I. G., and Philip W. Ind. “Effect of Cannabis Smoking on Lung Function and Respiratory Symptoms: A Structured Literature Review.” Primary Care Respiratory Medicine, vol. 26, 2016, doi:10.1038/npjpcrm.2016.71. Accessed 27 Nov. 2024.

“State Medical Cannabis Laws.” National Conference of State Legislatures, 12 July 2024, www.ncsl.org/health/state-medical-cannabis-laws. Accessed 27 Nov. 2024.

Van Laar, Margriet, et al. "Does Cannabis Use Predict the First Incidence of Mood and Anxiety Disorders in the Adult Population?" Addiction, vol. 102, no. 8, 2007, pp. 1251–60. Academic Search Complete, search.ebscohost.com/login.aspx?direct=true&db=a9h&AN=25640932&site=ehost-live. Accessed 22 June 2017.

Von Sydow, Kirsten, et al. “What Predicts Incident Use of Cannabis and Progression to Abuse and Dependence? A 4-Year Prospective Examination of Risk Factors in a Community Sample of Adolescents and Young Adults.” Drug and Alcohol Dependence, vol. 68, no. 1, 2002, pp. 49–64.