Marijuana Lecture Notes
Marijuana Overview
Introduction to Marijuana
Definition: Marijuana refers to cannabis products that contain THC (tetrahydrocannabinol), the primary psychoactive component of cannabis.
Scientific Name: The marijuana plant is scientifically known as Cannabis sativa.
Chemical Composition: Contains over 500 chemicals, including THC and cannabidiol (CBD), which does not produce a high.
Related Forms:
Hemp: Refers to cannabis products that contain very little THC.
Hashish: A concentrated form of cannabis containing high levels of THC.
Historical Overview
Brief History of Marijuana Use
Earliest Evidence: 10,000 years ago in the Stone Age, evidenced by pots made from cannabis plant fibers.
Medicinal Use:
c. 2700 B.C.: Chinese emperor and pharmacist Shen Nung documented medicinal cannabis use.
Use gradually spread from China to surrounding Asian countries, the Middle East, and Africa.
Cannabis in the Americas
1920s: Wider recreational use emerged, partly due to alcohol prohibition.
Tea-pads opened in New York City, functioning as social clubs for marijuana use.
Public Concern: Little concern until sensational articles emerged in 1926.
Legislation:
1932: Federal Bureau of Narcotics Director Harry Anslinger promoted anti-marijuana laws.
By 1937, nearly all states had laws prohibiting marijuana use.
1970s Onward: A gradual movement toward decriminalizing marijuana for personal and medicinal use has occurred.
Current Landscape: The legal landscape regarding marijuana is rapidly changing, notably as of April 2023.
Epidemiology
Marijuana Use Worldwide
Marijuana is the most widely used illicit drug in the Western world, following alcohol and tobacco as the third most used recreational drug.
UN Classification (2020): Cannabis reclassified to a less dangerous drug.
Highest Usage Rates:
Oceania > Africa > Americas > Europe > Asia.
Prevalence Trends: Lifetime use prevalence rates have gradually increased since the mid-1990s.
U.S. Trends
Marijuana Use Among Various Age Groups (2002-2019):
Rates of past year marijuana use increased among those aged 12 and older, with significant differences noted at the 0.05 level.
Lifetime Use Rates:
Higher rates observed in specific age groups such as those aged 12+, 18-25, aiming at an understanding of temporal usage changes.
Methods of Use
Common Methods of Using Marijuana and Hashish
Historically ingested in liquid and food forms or chewed as leaves.
Present-Day Popular Methods:
Smoking: Most common method in the U.S.
Vaping: Involves vaporization similar to e-cigarettes.
Dabbing: Involves heating hash oil and inhaling the vapor, often with safety risks of burns.
Usage Statistics (2022)
Modes of Past Year Marijuana Use Among Users Aged 12+:
Smoked marijuana: 78.4%
Ate marijuana: 36.7%
Vaped marijuana: 17.5%
Dabbed marijuana: 15.4%
Other modes: This includes various applications such as lotions, lozenges, and pills.
Active Ingredients
Cannabinoids and THC
Chemical Analysis History: First chemical analysis of cannabis conducted in 1821.
Cannabinoids: Over 500 individual compounds including about 60 known cannabinoids unique to cannabis.
THC Specifics:
Isolated in 1964 and considered the principal psychoactive agent.
D-9-THC accounts for the majority of the pharmacological actions of marijuana.
Other cannabinoids like CBD are biologically active and have FDA approval for certain medical uses like epilepsy.
Potency of Cannabis
THC content varies globally; U.S. marijuana generally has a lower THC content than that cultivated in other countries but has increased in potency.
Historical figures: THC content was c. 2% in 1980; now averages between 10-12%.
Hash Oil: Highly concentrated, can contain up to 60% THC.
Mechanisms of Action
Cannabinoid Receptors
Receptor Types: Two identified: CB1 and CB2.
CB1: Primarily found in brain areas related to memory, cognition, motor function, and mood.
CB2: Predominantly found in the immune system.
Endogenous Ligands:
Anandamide (AEA)
2-arachidonylglycerol (2-AG)
These are produced post-synaptically and not stored synaptically.
Tolerance and Dependence
Tolerance Findings
Human Research Findings on Tolerance:
Evidence varies; tolerance is likely with higher doses and longer durations of use.
Laboratory studies typically utilize higher doses than commonly reported in general populations.
Mechanisms of tolerance remain unknown, though cannabinoid receptor down-regulation and desensitization are candidates.
Physical Dependence Debate
Ongoing debate about withdrawal syndromes; some scholars argue significant withdrawal indicators are absent, while others note symptoms (sleep disturbance, irritability) linked to heavy use.
Medical and Psychotherapeutic Uses
Current Medical Applications
THC-Based Drugs:
Dronabinol (Marinol)
Nabilone (Cesamet)
THC + CBD Products:
Nabiximols (Sativex)
CBD-Based Medications:
Epidiolex
Future Directions: Drugs manipulating endocannabinoid activity are in the pipeline.
Physiological Effects
Acute Effects
Different Effects: Vary in intensity and duration among individuals but generally not dramatic in healthy users:
Cardiovascular: Vasodilation, bloodshot eyes, increased heart and pulse rates, elevated blood pressure.
Motor Function: General decrease in motor activity, with reports of drowsiness and increased talkativeness.
Effects can influence sleep patterns, particularly reducing total REM sleep at higher doses.
Minor physical effects may include dry mouth, thirst, fluctuations in breathing, increased appetite ("the munchies"), nausea, headaches, and dizziness.
Long-Term Effects
Respiratory System:
Possible increased risk of respiratory symptoms and chronic bronchitis episodes; typically reversible after stopping use.
Studies suggest no impairment of lung function with long-term use, nor an increase in lung cancer risk.
Cardiovascular System:
Healthy individuals present no harmful effects, although increased heart rates can be dangerous for those with pre-existing conditions.
Immune System:
No significant long-term threats noted.
Cannabis can act as an immunosuppressant, but its clinical significance in healthy individuals remains questionable.
Psychological Effects
Behavioral Effects
Generalized decrease in psychomotor activity, which is dose-related and aligned with relaxation and tranquility.
Some intensity perception enhancements reported by users, alongside decreased sensitivity to pain.
Subtle impairments in motor coordination can increase risks for driving, indicated by studies showing crash risks are elevated when driving under the influence.
Cognitive Effects
Most common side effect is impaired short-term memory; can occur even with low doses and increase with task complexity.
Adolescents may show greater vulnerability to memory impairment.
Time perception may be altered but to a lesser extent than subjectively reported by users.
Emotional Effects
Positive emotional effects frequently motivate cannabis use, with various non-pharmacological factors influencing these feelings.
Emotional outcomes can include carefree and euphoric feelings, often linked to relaxation and happiness—however, negative emotions and symptoms can also occur.
Social and Environmental Effects
Interpersonal Skills: Some reports suggest enhanced social competence; however, data shows insufficient support for this claim.
Effects on Aggression and Violence: Research supports that cannabis use does not cause increased aggression; aggression levels may decrease after use.
Amotivational Syndrome: Characterized by apathy and a loss of ambition; causation from cannabis remains unestablished.
Conclusion and Future Discussions
The ongoing exploration of cannabis effects and the respective social, psychological, and therapeutic implications continues to evolve, warranting further research.
Marijuana Overview
Origin, Source, and Production Uses
Definition: Marijuana refers to cannabis products containing THC (tetrahydrocannabinol), the primary psychoactive component.
Scientific Name: Cannabis sativa.
Earliest Evidence: 10,000 years ago in the Stone Age, evidenced by pots made from cannabis plant fibers.
Medicinal Use: Documented by Chinese emperor and pharmacist Shen Nung around 2700 B.C., spreading from China to Asia, the Middle East, and Africa.
Related Forms/Production: Hemp refers to cannabis products with very little THC, while hashish is a concentrated form with high THC levels.
Benefits (Medical Applications)
THC-Based Drugs: Dronabinol (Marinol) and Nabilone (Cesamet) are used for medical purposes.
THC + CBD Products: Nabiximols (Sativex) combines both THC and CBD.
CBD-Based Medications: Epidiolex has FDA approval for certain medical uses, such as epilepsy.
Future Directions: Research continues into drugs that manipulate endocannabinoid activity.
Relevant Routes of Administration
Historically: Ingested in liquid and food forms or chewed as leaves.
Present-Day Popular Methods:
Smoking: Most common method in the U.S.
Vaping: Involves vaporization similar to e-cigarettes.
Dabbing: Involves heating hash oil and inhaling the vapor, which carries safety risks of burns.
Eating: Consuming marijuana in food or liquid forms.
Other Modes: Includes various applications such as lotions, lozenges, and pills.
Usage Statistics (2022) Among Users Aged 12+:
Smoked marijuana: 78.4%
Ate marijuana: 36.7%
Vaped marijuana: 17.5%
Dabbed marijuana: 15.4%
Mechanism of Action
Cannabinoids: Over 500 chemical compounds are present, including about 60 known cannabinoids unique to cannabis. THC (D-9-THC) is the principal psychoactive agent.
Cannabinoid Receptors:
CB1: Primarily found in brain areas related to memory, cognition, motor function, and mood.
CB2: Predominantly found in the immune system.
Endogenous Ligands: Anandamide (AEA) and 2-arachidonylglycerol (2-AG) are naturally produced post-synaptically and are not stored synaptically.
Pharmacokinetics
Chemical Composition: Contains over 500 chemicals, including THC and cannabidiol (CBD). CBD does not produce a high.
Potency: THC content varies globally and has increased in the U.S.
Historical figures: THC content was approximately 2% in 1980.
Current average: Between 10-12%.
Hash Oil: Can contain up to 60% THC, indicating high concentration.
Acute Effects
Physiological Effects:
Cardiovascular: Vasodilation, bloodshot eyes, increased heart and pulse rates, elevated blood pressure.
Motor Function: General decrease in motor activity, drowsiness, increased talkativeness, subtle impairments in motor coordination (increasing risks for driving).
Sleep: Can influence sleep patterns, specifically reducing total REM sleep at higher doses.
Minor Physical Effects: Dry mouth, thirst, fluctuations in breathing, increased appetite ("the munchies"), nausea, headaches, and dizziness.
Cognitive Effects:
Short-Term Memory: Most common side effect is impaired short-term memory, even at low doses, increasing with task complexity.
Adolescents: May show greater vulnerability to memory impairment.
Time Perception: May be altered, though often to a lesser extent than subjectively reported.
Emotional Effects:
Positive emotions frequently motivate use, with feelings of carefree euphoria, relaxation, and happiness.
Negative emotions and symptoms can also occur.
Chronic Effects
Respiratory System: Possible increased risk of respiratory symptoms and chronic bronchitis episodes, typically reversible upon cessation. Studies suggest no impairment of lung function or increased lung cancer risk with long-term use.
Cardiovascular System: No harmful effects in healthy individuals, but increased heart rates can be dangerous for those with pre-existing conditions.
Immune System: No significant long-term threats noted. Cannabis can act as an immunosuppressant, but its clinical significance in healthy individuals is questionable.
Social and Environmental Effects:
Interpersonal Skills: Some reports suggest enhanced social competence, but data is insufficient to support this claim.
Aggression and Violence: Research suggests cannabis use does not cause increased aggression; aggression levels may decrease after use.
Amotivational Syndrome: Characterized by apathy and loss of ambition; causation from cannabis remains unestablished.
Tolerance
Findings: Evidence varies; tolerance is likely with higher doses and longer durations of use.
Mechanisms: Remain unknown, though cannabinoid receptor down-regulation and desensitization are candidates.
Dependence
Physical Dependence Debate: Ongoing debate regarding withdrawal syndromes. Some scholars argue a lack of significant withdrawal indicators, while others note symptoms like sleep disturbance and irritability linked to heavy use.
Major Use Trends
Worldwide: Marijuana is the most widely used illicit drug in the Western world, following alcohol and tobacco as the third most used recreational drug.
UN Classification (2020): Cannabis was reclassified to a less dangerous drug.
Highest Usage Rates: Oceania > Africa > Americas > Europe > Asia.
Prevalence Trends: Lifetime use prevalence rates have gradually increased since the mid-1990s.
U.S. Trends: From 2002-2019, rates of past year marijuana use increased among those aged 12 and older. Higher lifetime use rates are observed in specific age groups like 12+ and 18-25.
Variables Impacting Use
Legislation: Early efforts by Federal Bureau of Narcotics Director Harry Anslinger promoted anti-marijuana laws by 1937. A gradual movement toward decriminalizing marijuana for personal and medicinal use began in the 1970s. The legal landscape is rapidly changing, notably as of April 2023.
Historical Context: Wider recreational use emerged in the 1920s, partly due to alcohol prohibition.
Age Groups: Adolescents may show greater vulnerability to memory impairment. Use rates vary significantly across age groups (e.g., 18-25).
Potency: The increasing THC content over time (from approximately 2% to 10-12%) may influence usage patterns and effects experienced by users.
Emotional Motivations: Positive emotional effects are a frequent motivation for cannabis use, influenced by various non-pharmacological factors.
Mechanisms of Action
Cannabinoid Receptors
Receptor Types: Two identified: CB1 and CB2.
CB1: Primarily found in brain areas related to memory, cognition, motor function, and mood. These receptors are crucial for mediating the psychoactive effects of THC.
CB2: Predominantly found in the immune system, where they play a role in inflammation and pain. These receptors do not mediate psychoactive effects.
Endogenous Ligands: The body naturally produces compounds that interact with these cannabinoid receptors, known as endocannabinoids. These include:
Anandamide (AEA)
2-arachidonylglycerol (2-AG)
These endocannabinoids are unique because they are produced post-synaptically (after the signal has been received by a neuron) and are not stored in synaptic vesicles like most neurotransmitters. Instead, they are synthesized on demand from membrane lipids and then released into the synaptic cleft, traveling backward (retrograde signaling) to bind to CB1 receptors on the pre-synaptic neuron. This retrograde signaling mechanism is a key feature of the endocannabinoid system, allowing it to fine-tune neurotransmitter release.
Interaction with THC
THC Specifics: D-9-THC (tetrahydrocannabinol) is the principal psychoactive agent in marijuana. When ingested, THC mimics the action of the body's natural endocannabinoids, binding to and activating CB1 and CB2 receptors.
CB1 Receptor Activation: The activation of CB1 receptors by THC in the brain leads to the characteristic psychoactive effects, including altered memory, perception, mood, and motor coordination. By binding to these receptors, THC modulates the release of various neurotransmitters, affecting a wide range of brain functions.
CB2 Receptor Activation: THC's interaction with CB2 receptors in the immune system contributes to its anti-inflammatory and pain-relieving properties, without producing a high.
Impact on Neurotransmission: The endocannabinoid system, and consequently THC, acts as a neuromodulatory system, influencing the release of other neurotransmitters such as dopamine, serotonin, and GABA, thereby affecting numerous physiological processes and behaviors.