8.cannabis & nicotine

Psychology 335 Lecture Notes

Caffeine and Methylxanthines

Discriminative Stimulus Properties

  • Caffeine shows some generalization in effects to cocaine at low doses.

  • Dopamine (DA) blockers can inhibit discrimination at low doses.

  • In human studies, look-alike drugs such as caffeine and ephedrine demonstrate similar subjective effects.

Subjective Effects of Caffeine

  • Enhancements in feelings of:
      - Well-being
      - Alertness
      - Energy
      - Motivation for work
      - Self-confidence

  • Not merely alleviating withdrawal symptoms for naïve users.

  • Positive effects more pronounced at lower doses.

  • High doses via IV can be mistaken for cocaine.

Tolerance

  • Tolerance develops with increasing doses of caffeine and is characterized by:
      - Increased generation of adenosine receptors.
      - Chronic usage can shift the dose/response curve significantly (up to 6 times).
      - Subjective effects can be tolerated within 4 days of ceasing use.

Withdrawal Symptoms

  • Withdrawal may lead to:
      - Decreased locomotor activity.
      - Symptoms may develop in a few weeks after cessation including headaches, drowsiness, and decreased energy.
      - Onset of symptoms: 12-28 hours; duration can last 2-9 days.
      - Withdrawal can be mistakenly attributed to cold-like symptoms during schedule changes (e.g., holidays).

Study on Withdrawal Effects

  • Changes in headache frequency and scores on an energy/activity scale were observed:
      - Subjects consumed 100-mg caffeine capsules, transitioned to placebo, and then back to caffeine.

Self-Administration in Humans

  • Caffeinated coffee and capsules serve as reinforcers, especially among habitual coffee drinkers.

  • Withdrawal avoidance is a primary factor in self-administration.

  • Caffeine Dependence Syndrome: Indicators include withdrawal, tolerance, desire to quit, and usage despite health issues.

  • Caffeine considered the most valuable commodity after oil, with an average global consumption of about 70 mg per person per day. In North America, the average is over 200 mg.

Harmful Effects of Caffeine

  • Reproductive Effects:
      - Reduces blood flow to the fetus, may lower birth rate and affect breast milk.

  • Cardiac Effects:
      - Possible increase in blood pressure and debated issues regarding heart disease association.

  • Anxiety Disorders:
      - Can precipitate disorders such as panic disorder.

Caffeinism

  • Characterized by anxiety-related symptoms, notably during stage fright.

  • Lethal doses of caffeine are estimated to be between 3 and 8 grams (30 to 80 cups of coffee), potentially leading to convulsions and respiratory failure.

Cannabinoids

Types of Cannabinoids

  1. Endocannabinoids (naturally occurring in animals):
       - Anandamide
       - 2-Arachidonoylglycerol (2-AG)

  2. Phytocannabinoids (derived from plants):
       - THC (Delta-9-tetrahydrocannabinol)
       - CBD (Cannabidiol) and many others.

  3. Synthetic Cannabinoids:
       - K9, Spice.

Historical Context

  • China: First recorded use attributed to Shen-Nung around 2700 B.C.

  • India: Cannabis referred to in the Vedas as a source of joy and liberation.

  • Europe: Introduced by William Brooke O'Shaughnessy in1841, enhancing medical discussions.

Cannabis Prohibition History

  • Harry Anslinger(1937) claimed marihuana causes insanity, influencing public opinion against it.

Cannabis Regulation in Canada

  • 2001: Introduction of the Marihuana Medical Access Regulations (MMAR) allowing access for medicinal purposes.

  • 2014: Transition to the Marihuana for Medical Purposes Regulations (MMPR), which streamlined applications and allowed licensed producers.

  • C-45: The Cannabis Act:
      - Governed retail sales and distribution, establishing a framework with age restrictions and penalties for violations.

Cannabinoids Overview

  • Cannabinoids like THC show a range of effects varying in dose and method of intake.

  • CBD is well-documented for its medical benefits while not activating CB1 or CB2 receptors directly.

Therapeutic Applications

  • CBD has shown promise in:
      - Anti-epileptic effects,
      - Analgesic and anti-inflammatory properties,
      - Psychotropic conditions including bipolar disorder and anxiety.

Effects on Behavior and Cognition

  • Subjective Effects: Can induce mood changes; no enhancement in creativity found.

  • Memory Impact: It may disrupt short-term recall but not affect long-term memory.

  • Performance Results: Mixed findings on cognitive tasks, suggesting more testing is required.

Cannabis Use Disorder (CUD) Diagnostic Criteria

  • Defined by the pattern of use leading to significant impairment or distress, with specific criteria such as tolerance and withdrawal symptoms.

Overdose and Driving Impact

  • Overdose reports highlight adverse effects mostly related to edibles.

  • Cannabis has complex effects on driving with experienced users showing no significant impairment compared to inexperienced ones.

Conclusion

  • Ongoing research indicates some benefits of cannabis in therapeutic settings, alongside necessary caution regarding potential risks such as psychosis in vulnerable populations. Further studies are required to clarify the complex nature of cannabis effects on mental and physical health.