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Effects of Marijuana by Dr. Zach, ER Physician MUHC

BT Montreal | posted Tuesday, Mar 13th, 2018

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
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
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
●Slurred speech

Acute side effects
Numbness, dizziness, low blood pressure, dysphoria (state of unease), anxiety, confusion,
vision changes, psychosis, 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.

  • Smoking
  • Alcohol
  • Opiates (gateway vs just ppl who take more drugs)
  • Stimulants
  • Mood disorders
  • Schizophrenia (increased risk if taken before 19)
  • Anxiety disorders, ocd, ptsd, adhd
  • Personality disorders (borderline, schizotypal, antisocial)

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 have been reported up to 10 days after weekly use and up to
25 days for after daily use
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
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
  • 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
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

  • 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

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 hospitalizations
  • 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.

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

  • 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

Pros of legalization — regulation (know what exactly you’re getting), taxation
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:


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