Dr. Zach Levine

March, 2018


Questions/topics for discussion:


  1. What is marijuana and what does it do?  How common is use?
  1. Mental effects
  2. Physiological effects
  3. Side effects
  4. Long-term effects and abuse


  1. Medical uses


  1. Legalization
  1. What will the law be (specify driving issues), testing
  2. Pros and cons
  3. Lessons from places where it is legal


Marijuana, hashish (hash) and hash oil come from cannabis sativa, a type of hemp plant. All three contain THC, a chemical that changes the way you think, feel and act. The word “cannabis” is used to refer to all three.

  • Marijuana is made from the dried leaves and flowering tops of the plant.
  • At a certain stage in the growth of the plant, before the flowers are mature,they become coated with a sticky resin. The resin can be dried to make hash.


Street names:

Weed, herb, chronic, jay, bud, blunt, bomb, doobie, hydro, sinsemilla, hash, joint, pot, grass, reefer, Mary Jane (MJ), ganja, homegrown, dope, spliff


  • Marijuana is the most commonly used illegal drug in Canada.
  • Almost half (44%) of Canadians say they have used marijuana at least once in their lifetime.

By age 17 about 46% of Canadian students have tried marijuana


Cannabis (also called marijuana) is the most commonly used illegal psychoactive substance worldwide. Its psychoactive properties are primarily due to one cannabinoid: delta-9-tetrahydrocannabinol (THC); THC concentration is commonly used as a measure of cannabis potency

Cannabis was used by an estimated 182 million people (range 128 to 234 million) worldwide in 2014, approximately 3.8 percent (range 2.7 to 4.9 percent) of the global population age 15 to 64 years.

The potency of cannabis has increased significantly around the world in recent decades, which may have contributed to increased rates of cannabis-related adverse effects. Cannabis use disorder develops in approximately 10 percent of regular cannabis users, and may be associated with cognitive impairment, poor school or work performance, and psychiatric comorbidity such as mood disorders and psychosis.

Men use more, people 12-25 use more.


Acute effects:


Cannabis intoxication in adolescents and adults also results in the following neuropsychiatric effects:

  • Mood, perception, thought content – Ingestion typically leads to feeling “high,” marked by a euphoric, pleasurable feeling and a decrease in anxiety, alertness, depression, and tension. However, first-time cannabis users, as well as anxious or psychologically vulnerable individuals, may experience anxiety, dysphoria, and panic. Increased sociability usually occurs during intoxication, although dysphoric reactions may be accompanied by social withdrawal. Inexperienced users who ingest cannabis products may not be aware that effects may not be felt for up to three hours which may cause them to continue to consume high potency products with an increased likelihood of dysphoria.

Perceptual changes include the sensation that colors are brighter and music is more vivid. Time perception is distorted in that perceived time is faster than clock time. Spatial perception can also be distorted, and high doses of potent cannabis products may cause hallucinations. Mystical thinking, increased self-consciousness, and depersonalization may occur, as well as transient grandiosity, paranoia, and other signs of psychosis.


  • Cognition, psychomotor performance – Cannabis use increases reaction time and impairs attention, concentration, short term memory, and risk assessment. These effects are additive when cannabis is used in conjunction with other central nervous system depressants.  Acute cannabis use also impairs motor coordination and interferes with the ability to complete complex tasks that require divided attention.

Impairment of cognition, coordination, and judgment lasts much longer than the subjective mood change of feeling “high.” Psychomotor impairment lasts for 12 to 24 hours. However, a marijuana user may think that he or she is no longer impaired several hours after the acute mood altering effects have resolved. As an example, a placebo controlled trial with licensed pilots found that smoking marijuana impaired performance on a flight simulator for up to 24 hours, although only one of the nine subjects possessed self-awareness of this.

Acute psychomotor impairments interfere with the ability to operate other heavy machinery, such as automobiles, trains, and motorcycles. A meta-analysis of nine studies found an association between cannabis intoxication and an increased risk of a motor vehicle collision involving serious injury or death. Drivers using cannabis are two to seven times more likely to be responsible for accidents compared to drivers not using any drugs or alcohol. Furthermore, the probability of causing an accident increases with plasma levels of delta-9-tetrahydrocannabinol.


Children — In children, acute marijuana intoxication typically occurs after exploratory ingestion of marijuana intended for adult use. Less commonly, intentional exposure of children by caretakers, including encouragement of cannabis inhalation to promote sleepiness and to decrease activity, has been reported. Pediatric ingestions of marijuana products happen more frequently in regions with decriminalization or legalization of cannabis use.

After limited exposures, children may display sleepiness, euphoria, irritability, and other changes in behavior. Vital signs may show sympathomimetic effects (eg, tachycardia and hypertension) or, in patients with depressed mental status, bradycardia. Nausea, vomiting, conjunctival injection, nystagmus, ataxia, and, in verbal children, slurred speech may also be present. Dilated pupils have frequently been reported, although miosis has also been described.

In large overdoses (eg, ingestion of edible products, concentrated oils, or hashish), coma with apnea or depressed respirations can occur.

Although not typical of pediatric cannabis intoxication, seizures have also been reported. In one instance, cocaine was also found on urine screening.


Adolescents and adults — The physiologic signs of cannabis intoxication in adolescents and adults include:

  • Tachycardia (fast heart rate)
  • Increased blood pressure or, especially in the elderly, orthostatic hypotension
  • Increased respiratory rate
  • Conjunctival injection (red eye)
  • Dry mouth
  • Increased appetite
  • Nystagmus
  • Ataxia
  • Slurred speech


Acute “side effects” (the effects people don’t want)

Numbness, dizziness, low blood pressure, dysphoria (state of unease), anxiety (yes even though in some people it decreases anxiety), confusion, vision changes, psychosis, hallucinations, speech disorder


Complications associated with inhalation use include:

  • Acute exacerbations and poor symptom control in patients with asthma.
  • Pneumomediastinum (air around the heart) and pneumothorax (air around/outside the lungs).
  • Rarely, angina and myocardial infarction.

The risk for myocardial infarction among regular cannabis users has been found to be as high as 4.8 times baseline.


Long term use concerns:

Psychosocial functioning and health — Adolescent cannabis use is strongly associated with lower educational attainment and increased use of other drugs, but not with school performance or psychological health; even the strong associations are not clearly causal:


Not strong evidence that is is a cause of cancer, heart attack, stroke, arteritis, atrial fibrillation but Gordon and colleagues said, “there does appear to be an increased risk of cancer (particularly head and neck, lung, and bladder cancer) for those who use marijuana over a period of time, although what length of time that this risk increases is uncertain.”[6]

Causes hyperemesis (vomiting) syndrome, tx with haldol or hot shower/bath (or fluids, antiemetics (ondanzatron), benzos)


Comorbidities (these things more common in marijuana users):



Opiates (gateway vs just ppl who take more drugs)


Mood disorders

Schizophrenia (increased risk if taken before 19)

Anxiety disorders, ocd, ptsd, adhd

Personality disorders (borderline, schizotypal, antisocial)


Medical uses:


Only evidence for efficacy in these conditions — Chemotherapy-induced nausea and vomiting, neuropathic pain, palliative cancer pain, and MS or spinal cord injury-related spasticity.


In neuropathic pain, palliative cancer pain, CINV, and MS- or SCI-related spasticity, they should only be considered for patients whose conditions are refractory to standard medical therapies. When considered, there should be a discussion with patients regarding the limited benefits and more common harms, and a preferential trial of pharmaceutical cannabinoid first (over medical marijuana).


Plans for cannabis laws in Canada once legalized:

Controlled access

Should the Cannabis Act become law in July 2018, adults who are 18 years or older would be able to legally:

  • possess up to 30 grams of legal dried cannabis or equivalent in non-dried form
  • share up to 30 grams of legal cannabis with other adults
  • purchase dried or fresh cannabis and cannabis oil from a provincially-licensed retailer
    • In those provinces that have not yet or choose not to put in place a regulated retail framework, individuals would be able to purchase cannabis online from a federally-licensed producer.
  • grow up to 4 cannabis plants per residence for personal use from licensed seed or seedlings
  • make cannabis products, such as food and drinks, at home provided that  organic solvents are not used

The sale of cannabis edible products and concentrates would be authorized no later than 12 months following the coming into force of the proposed legislation.


Strict Regulation


QC law:


Under the new plan, the legal age to buy, possess and consume marijuana in Quebec will be 18 — the same as the drinking age.

Other key points include:

  • No one will be allowed to grow cannabis for personal use. It will also be banned to grow it for commercial use, unless following the laws set out by the government.
  • It must be smoked in the same places as tobacco. Smoking will also be prohibited on university and CEGEP grounds.
  • There will be zero tolerance for drivers — police officers will be able to ask for a saliva sample if they suspect someone is driving while high and will be able to suspend a driver’s licence for 90 days if a sample comes back positive for ANY cannabis.

While saliva testing has yet to be federally regulated, the province says that police officers are being trained to detect signs of marijuana-impaired driving.


The Quebec law would set the legal age at 18 and allow individuals to transport up to 30 grams at a time and hold 150 grams at home


A government agency, the Société québécoise du cannabis, will have exclusive legal control of recreational use, selling the product through a limited number of storefronts and online. The province will have 15 stores ready by July 1 and up to 150 in two years.


Testing for cannabis in the body:


Urine drug screens are less helpful in adolescents and adults for the diagnosis of acute intoxication. Although testing is usually positive several hours after acute exposure it can also be positive well after symptoms have resolved. As an example, positive results for delta-9 tetrahydrocannabinol metabolites (urine test) have been reported up to 10 days after weekly use and up to 25 days for after daily use


Saliva swab test positive for 6-12 hrs after use

Blood test shows level, positive for 36 hrs after use


Laws re driving high Canada:

Drivers caught with more than five nanograms of THC in their blood would be guilty of impaired driving, while drivers with both alcohol and THC in their system would be considered impaired if they have more than 50 miligrams of alcohol (per 100 mililitres of blood) and greater than 2.5 nanograms of THC in their blood.

The government said the other two proposed offences would be similar to the offences for drunk driving. Drivers with more than five nanograms of THC in their blood would be punished with a mandatory fine of $1,000 for a first offence, 30 days imprisonment for a second offence and 120 days for a third offence.


Legalization results elsewhere:


The public health impact of decriminalization or legalization of recreational cannabis use include:


  • Both decriminalization and legalized recreational use have been associated with increased unintentional pediatric ingestions. As an example, after legalization of recreational marijuana use in Colorado, annual calls to the regional poison control center for pediatric marijuana exposure increased 34 percent on average to 6 cases per 100,000 population, which was almost twice the rate for the rest of the United States.  Exposure to recreational marijuana accounted for about half of cases. Rates of hospital visits at a large regional children’s hospital system also increased significantly during the period of the study, although the total number of presenting patients (81) was small.


  • In regions with medical marijuana availability, diversion of drug from registered users may also encourage adolescent abuse.


  • In other countries where cannabis can be used legally, rates of usage vary. For example, in the Netherlands, the overall annual prevalence of cannabis usage is 23 percent among young adults compared with 5 percent annual usage reported by persons 12 to 64 years of age in Uruguay. Thus, the impact of decriminalization or legalization on the subsequent prevalence of cannabis usage is not easily predicted and varies depending upon the specifics of regulatory enactment.


Experience in places where pot is legalized — In Washington and Colorado:


Rising rates of pot use by minors

Increasing arrest rates of minors, especially

black and Hispanic children

Higher rates of traffic deaths from driving

while high

More marijuana-related poisonings and


A persistent black market


The THC content, or potency, of marijuana,

as detected in confiscated samples, has been

steadily increasing from about 3% in the 1980s

to 12% in 2012



Arguments in favour of legalization — regulation (know what exactly you’re getting), taxation


Argument against — increased amount of a potentially harmful drug, government sanctioning


Negative effects:  addiction, worse cognitive function, poss long term brain function effects


Marijuana use has been associated with substantial adverse effects, some of which have been determined with a high level of confidence.  Marijuana, like other drugs of abuse, can result in addiction. During intoxication, marijuana can

interfere with cognitive function (e.g., memory and perception of time) and motor function (e.g.,coordination), and these effects can have detrimental consequences (e.g., motor-vehicle accidents). Repeated marijuana use during adolescence may result in long-lasting changes in brain function that can jeopardize educational, professional, and social achievements. However, the effects of a drug (legal or illegal) on individual health are determined not only by its pharmacologic properties but also by its availability and social acceptability. Alcohol and tobacco are legal and account for the greatest burden of disease due to drugs.


Cannabis use disorder: the continued use of cannabis despite clinically significant impairment, ranging from mild to severe

The main risk factors for cannabis abuse 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


The school experience strongly influences risk of cannabis use or vice versa. Among adolescents enrolled in school, two- threefold greater prevalence of cannabis use during the past month is seen among adolescents with (compared with without) the following characteristics:

  • Failing grades
  • Nonparticipation in extracurricular activities
  • Dislike of school
  • Others in grade who use cannabis, alcohol, or cigarettes

ie regular cannabis users in adolescence increases risk of poor school performance


  • Employment status – Those employed full-time or not in the labor force (eg, students, retired, disabled) have lower prevalence of cannabis use during the past month than do those working part-time (11.6 percent) or unemployed (7.5 and 4.8 versus 15 percent).
  • Income – Adults with income less than $20,000 USD annually have 2.5-times higher rates of cannabis use during the past year than adults with income of at least $70,000 USD annually (15.6 versus 5.9 percent).
  • Marital status – Unmarried adults are more likely to have used cannabis during the past year than are married adults or those widowed/separated (21.0 versus 5.5 versus 8.3 percent).
  • Legal status – Adults on parole, probation, or supervised release status are approximately three times more likely to have used cannabis in the past month than are individuals not in such legal status. Adolescents with violent or illegal behavior in the past year are at least twice as likely as those without such behavior.
  • Social network – Among adolescents, a positive relationship with parents and having parents, friends, or peers who disapprove of cannabis use are all associated with at least twofold lower prevalence of cannabis use over the past month.
  • Religion – Adolescents with frequent attendance at religious services or strong religious beliefs are two to three times less likely to have used cannabis over the past month than those without such protective factors.
  • Other substance use – Cigarette smokers and alcohol drinkers are each five to six times more likely than nonsmokers and nondrinkers to use cannabis.
  • Geography – Prevalence of cannabis use over the past month in the United States varies somewhat by geographic characteristics. Highest rates are found in New England (11.0 percent) and the West (10.3 percent) and in large (>1 million population) metropolitan areas (8.7 percent). Lowest rates are found in the South Central region (5.9 percent) and in rural areas (4.5 percent).


But Cannabis use disorder constitutes a small proportion of the global burden of disease relative to other substance use disorders. Of the approximately two million total disability adjusted life-years lost to substance use disorders (not including tobacco), individual substance use disorders were:

  • Alcohol – 47 percent
  • Opioids – 24.3 percent
  • Amphetamines – 7.0 percent
  • Cannabis – 5.5 percent
  • Cocaine – 2.9 percent
  • Other illicit drugs – 13.4 percent


Large-scale cross-sectional epidemiological studies and smaller prospective longitudinal studies have not found cannabis use to be significantly associated with serious or chronic medical conditions or death from medical conditions.


Canadian medical college marijuana prescribing guidelines, authorized producers, more info: