Cannabis Use Disorder

• About 1 in 7 Canadians aged 15 and over reported using cannabis in the past year.
• Based on the DSM-5, the 12-month prevalence of cannabis use disorder in the United States is about 3.4% among 12- to 17-year-olds, and 1.5% among adults.^[1]
  • In the past decade, due to perceptions of the “low-risk” of cannabis use, and legalization worldwide, the prevalence has increased in both adults and adolescents.
• Cannabis use disorder is greater in adult males (2.2%) than females (0.8%).^[2]
• The onset is most commonly during adolescence or young adulthood.

• Very early use of cannabis (<15 years old) is a reliable predictor for the development of cannabis use disorder, other substance use disorders, and mental disorders (e.g. - psychosis and schizophrenia).^[3]
• For adolescence and young adults, school difficulties are commonly in cannabis use disorder
  • There can be a dramatic drop in grades, truancy, and reduced interest in school activities and outcomes.
• Generally, tolerance is lost when cannabis use is stopped for at least several months.^[4]
• Chronic cannabis use is linked to a reduction in prosocial goal-directed activities (“amotivational syndrome”) which can cause poor school and/or employment performance.
• Accidents while during cannabis intoxication (e.g. - driving) are also a risk for safety.
• Despite public perception of low risk, smoking/inhalation of cannabis can still deliver high levels of carcinogenic compounds that increase the risk for respiratory diseases (similar to tobacco smokers).^[5]
• The risk for cannabis use and psychosis, and onset of schizophrenia is under investigation (see section below).

• Individuals who use cannabis regularly may have mood, sleep, pain, or other physical or mental health symptoms, and there is an increased risk for concurrent mental disorders.
• There is more often than not another comorbid substance use disorder.
  • There are high rates of alcohol use disorder and tobacco use disorder (both >50%).
  • Other increased substance use disorders stimulants (cocaine, methaphetamine) and opioids.
• Major depressive disorder (11%), anxiety disorders (24%), and bipolar I disorder (13%) are common.
• Antisocial (30%), obsessive-compulsive, (19%), paranoid (18%) personality disorders are common.^[6]

• Conduct disorder and antisocial personality disorder are risk factors for developing substance use disorders.^[7]
• Psychiatric disorders (both externalizing and internalizing disorders) are also risk factors.
• Unstable or abusive family environments, use of cannabis in close family members, family history of a substance use disorders, increase ease of access, and low socioeconomic status are risk factors.
• Heritable factors are thought to contribute 30 to 80% of the total variance in risk for cannabis use disorder.^[8]

• Other names commonly used for cannabis include “pot,” “weed,” “herb,” “reefer,” “mary jane,” “dagga,” “dope,” “bhang,” “skunk,” “boom,” “gangster,” “kif,” and “ganga.”
• There are also cannabis-like substances, including synthetic cannabinoids (e.g. - prescription nabilone)

• Cannabis consists of primarily two constituents: ∆9-tetrahydrocannabinol (THC) and cannabidiol (CBD)
  • ∆9-tetrahydrocannabinol (THC) is the principal psychoactive constituent of cannabis.
  • Contrast this with cannabidiol (CBD), which is not intoxicating and does not have the same psychoactivity as THC. CBD may play a role in the treatment of psychiatric and neurological disorders, and is under investigation.
• Cannabinoids have many effects in the brain, and its main actions are on the CB1 and CB2 cannabinoid receptors in the central nervous system. The brain also produces its own endogenous ligands for these receptors, which act similar to neurotransmitters.

A problematic pattern of cannabis use leading to clinically significant impairment or distress, as manifested by at least 2 of the following, occurring within a 12-month period:

1. Cannabis is often taken in larger amounts or over a longer period than was intended
2. There is a persistent desire or unsuccessful efforts to cut down or control cannabis use
3. A great deal of time is spent in activities necessary to obtain cannabis, use cannabis, or recover from its effects
4. Craving, or a strong desire or urge to use cannabis
5. Recurrent cannabis use resulting in a failure to fulfill major role obligations at work, school, or home
6. Continued cannabis use despite having persistent or recurrent social or interpersonal problems caused or exacerbated by the effects of cannabis
7. Important social, occupational, or recreational activities are given up or reduced because of cannabis use
8. Recurrent cannabis use in situations in which it is physically hazardous
9. Cannabis use is continued despite knowledge of having a persistent or recurrent physical or psychological problem that is likely to have been caused or exacerbated by cannabis
10. Tolerance, as defined by either of the following:
    • A. A need for markedly increased amounts of cannabis to achieve intoxication or desired effect.
    • B. Markedly diminished effect with continued use of the same amount of cannabis.
11. Withdrawal, as manifested by either of the following:
    • A. The characteristic withdrawal syndrome for cannabis (refer to Criteria A and B of the criteria set for cannabis withdrawal).
    • B. Cannabis (or a closely related substance) is taken to relieve or avoid withdrawal symptoms.

• Individuals may use cannabis throughout the day over a period of months or years, and can spend several hours intoxicated.

• Cannabis is most commonly smoked using pipes, water pipes (bongs/hookahs), cigarettes (joints/reefers), rolled paper (blunts), or through oral edibles.^[9]
  • Developments in vaporizer technology has also led to increased use via vaporization for inhalation, which produces a more rapid onset and intense effect.
• During the past two decades, the potency (THC component specifically) of cannabis has been gradually increasing.^[10]
  • The potency of THC ranges greatly, from 1 to 15% in the typical cannabis plant material and up to 10 to 20% in hashish (cannabis concentrate)
• Oral formulations (pill/capsules) of delta-9-tetrahydrocannabinol (delta-9-THC) are prescribed for a number of approved medical indications (e.g. - for nausea and vomiting caused by chemotherapy; for anorexia and weight loss in AIDS).^[11]

• Cannabis use is associated with future risk for being diagnosed with an anxiety disorder, with the greatest association in young males.^[12]

• There is increasing evidence to suggest a link between cannabis use and its effect on accelerating the onset of schizophrenia in vulnerable individuals. This is especially true with cannabis use during puberty.^[13]
• Whether it is a true cause-and-effect remains under investigation, but recent population studies have shown that almost 50% of individuals with an episode of cannabis-induced psychosis will go on to develop schizophrenia or bipolar disorder.^[14]

• Cannabis use is associated with increased risk of myocardial infarction and stroke.^[15]

• Like with all substance use disorders, there is a complex interplay between biological, social, psychological, and cultural factors.

• Non-problematic use of cannabis
  • The distinction between non-problematic use of cannabis and cannabis use disorder can be difficult to make because social, behavioural, or psychological problems may be difficult to attribute to the substance, especially if there are other substances in the picture.
• Depressive disorders
  • Chronic use of cannabis can produce a lack of motivation that resembles persistent depressive disorder (dysthymia).
• Other mental disorders
  • Cannabis-induced disorder may be characterized by symptoms (e.g. -anxiety) that resemble primary mental disorders (e.g. - generalized anxiety disorder).
  • Acute adverse reactions to cannabis should be differentiated from panic disorder, delusional disorder, bipolar disorder, or schizophrenia.

• Tests for cannabinoid metabolites can determine recent cannabis use.
• Since cannabinoids are fat soluble, they can remain in bodily fluids for extended periods of time and are excreted slowly (e.g. - chronic use can result in cannabis being detectable for several weeks even after stopping use).

• There are no approved pharmacological treatments for cannabis use disorder.
  • THC preparations, cannabidiol (CBD), N-acetylcysteine, oxytocin are probably ineffective for stopping cannabis use.^[16]
  • The effects of anticonvulsants and mood stabilizers remain uncertain, as they may increase study dropouts but do not appear to cause more severe side effects.^[17]
• The main treatment remains psychosocial management, and use of psychotherapies such as motivational interviewing (MI), cognitive behavioural Therapy (CBT), mindfulness-based relapse prevention (MBRP), and contingency management (CM).^[18]