Addiction

Categories of Drugs

  • Common Characteristics:

    • Stimulants: Arouse and excite activity

    • Narcotics: Induces narcosis/sleep/stupor

    • Hallucinogens: Produces hallucinations.

  • Drug Categories:

    • Cocaine: Stimulant

    • MDMA: Stimulant and hallucinogen

    • Morphine: Narcotic

    • Heroin: Narcotic

    • Amphetamines: Stimulant

    • Fentanyl: Narcotic

    • LSD: Hallucinogen

    • Nicotine: Stimulant

    • Ritalin: Stimulant

    • Codeine: Narcotic

    • Psilocybin: Hallucinogen

    • Mescaline: Hallucinogen.

Australian Drug Use Statistics

  • Concern over Methamphetamine: Increased potency despite falling overall use.

  • Trends Among Students (Years 10-12): General downward trend in drug use.

  • 2022/2023 Survey Findings: Increased use of hallucinogens and Ketamine; decreased use of opioids and ecstasy.

  • Reasons for Drug Use: Curiosity for initiation, enjoyment of effects for continuation.

Pharmacology and Addiction

  • Dopamine Signal Changes: Increases initially, diminishes as rewards become predictable.

  • Self-Stimulation Regions: Median Forebrain Bundle, Nucleus Accumbens, Lateral Hypothalamus.

  • Mechanism of Addictive Drugs: Increase dopamine in Nucleus Accumbens.

  • Cocaine's Effect: Blocks dopamine reuptake transporter (DAT).

  • Amphetamines: Reverse monoamine transporters and inhibit Monoamine Oxidase.

  • Cannabis: THC binds to cannabinoid receptors, inhibiting GABA release in VTA.

  • Nicotine: Stimulates Nicotinic receptors, enhancing dopamine release.

Long Term Effects

  • MDMA's Impact: Short-term serotonin depletion leads to depression; repeated use risks neurotoxicity and chronic mood issues.

Substance Use Disorders

  • Definitions:

    • Tolerance: Decreased drug effectiveness with repeated use.

    • Withdrawal: Symptoms from cessation of chronic use (physical dependence).

    • Craving: Desire for drug in its absence (psychological dependence).

  • Incentive-Sensitization Theory: Craving becomes dominant over time.

  • Limitations of Dopamine Theory: Aversive stimuli also release dopamine; not all users become addicted.

  • Brain Regions Affected by Stimulants:

    • Increased activity in Nucleus Accumbens, Hippocampus, Amygdala (memory), Dorsal Striatum (habits).

    • Decreased activity in Prefrontal Cortex (exec. function); increased in Orbitofrontal Cortex (reward assessment). Glutamate connections regulate craving.