psych drugs & behaviour tolerance Study Notes on Tolerance and Addiction

Substance Use and Tolerance

  • General Concept

    • Tolerance is defined as the body's reduced response to a drug after repeated use, necessitating increased dosages to achieve similar effects.
    • Development of tolerance can be seen in various substances and can vary significantly between drugs.

  • Examples of Tolerance

    • Alcohol: May initially create dizziness, but a person may develop tolerance to this effect while remaining sensitive to other health impacts like liver damage.
    • Cross Tolerance: Occurs when tolerance to one drug extends to another, e.g., a user tolerant to alcohol may find themselves tolerant to benzodiazepines due to similar effects on the nervous system.

  • Types of Tolerance

    • General (Nonspecific) Tolerance: Affects overall drug effectiveness; exemplified by metabolic tolerance, where the body becomes more efficient at processing the drug (enzyme induction).
      • Mechanism: After repeated use, the body can increase the production of enzymes that metabolize the drug faster, thereby reducing its effective concentration at the site of action.
    • Specific Tolerance: Tolerance to certain effects of a drug while other effects remain unaffected; e.g., tolerance to the euphoric effect of alcohol does not indicate the liver damage persists.

  • Acute Tolerance

    • Defined as rapid tolerance development during a single drug experience, illustrated by the drug effect peak occurring before blood concentration levels:
    • Drug levels rise, but subjective effects start to diminish, reflecting a physiological adjustment to the drug.

  • Cross Tolerance

    • The phenomenon where tolerance to one substance (e.g., a psychedelic) may lessen the effects of a second, different substance (e.g., another psychedelic) taken in close succession.
    • Example: After a strong acid trip, an individual may struggle to feel the effects of mushrooms due to previous exposure to similar drugs.

  • Physiological Effects of Tolerance

    • Cellular Tolerance: Related to up-regulation or down-regulation of neurotransmitter receptors in response to prolonged drug use, which can lead to withdrawal and cravings when the drug is withheld.
    • Behavioral Tolerance: Represents learned adjustments to drug effects, e.g., learning to behave normally in the presence of drugs (cognitive strategies to hide intoxication).

  • Withdrawal

    • Definition: Physical and psychological responses that occur when drug use is stopped; usually manifests as a compensatory disturbance in homeostasis.
    • Withdrawal symptoms can include cravings, anxiety, and physiological discomfort that is often opposite the effects of the drug (e.g., opioid withdrawal may cause pain).

  • Physical vs. Psychological Dependence

    • Physical dependence is characterized by withdrawal signs after cessation of drug use, while psychological dependence is more nebulous and does not always conform to observable withdrawal symptoms.
    • Distinction between the two is crucial, especially in the context of addiction.

  • Hangover vs. Withdrawal

    • Though hangovers can include withdrawal symptoms, they are typically the outcome of substance use effects (e.g., dehydration from alcohol) rather than cessation.

  • Elasticity of Tolerance

    • Tolerance tends to reset after abstinence; post-abstinence, individuals may find previous dosages are now unmanageable (e.g., individuals after a period of recovery from alcohol being especially sensitive to its effects).

  • Factors Influencing Tolerance

    • Genetic Factors: Some individuals inherit traits (e.g., enzyme production differences) that influence both metabolism and tolerance.
    • Environmental Context: Drug contexts that provide cues associated with drug experience can impact tolerance levels; familiar environments may trigger compensatory physiological responses before a drug is consumed.
    • Functional Disturbances: As the body experiences increased pressures (e.g., stress), it may adapt by developing specific tolerances to casualties and other effects.

  • Neuropsychological Mechanisms

    • Brain areas such as the nucleus accumbens, related to reinforcement processing and dopamine activity, involvement in compulsive behaviors.
    • Independent cognitive areas indicate learned associations between drug use and environmental contexts that can lead to relapse through conditioned responses (e.g., cravings elicited by drug-related cues).

  • Addiction as Disease

    • Conceptualized through the lens of the DSM: addiction characterized by impaired control, social impairment, risky use, and physiological criteria of tolerance and withdrawal.
    • Compulsion and neurological changes induced can blur the lines of free will; understanding addiction within the context of disease — where treatment may be necessary due to compulsive behaviors resulting from physiological changes in brain structures affecting motivation and decision-making.

  • Conclusion

    • The discussion on addiction underscores a critical behavioral syndrome, where substances commandeer motivation, shifting normal reinforcements away from healthy engagements in life towards drugs, resulting in a place characterized by a motivational toxicity preventing normal decision-making actions.