Summary #4 drugs and addiction
Drug:
An exogeneous chemical, not necessary for normal cellular functioning, that significantly
alters the function of cells of the body when taken in relatively low doses.
Psychopharmacology:
Chemicals that affect nervous system (therapeutic or drugs of abuse)
Effect of drugs change physiological/behavioral processes
Common drugs are derived from plants (the chemicals that are present in plants)
Drugs can have various effects on NT’s
These effects may facilitate or inhibit the original (goal of the) NT.
Facilitate (mimic/increase NT or receptor) agonist
Inhibit (block NT/receptor antagonist
A drug is not either, but has mixed functions (e.g., it may facilitate 1 NT and inhibit another
OR, be an agonist for some doses but an antagonist for others)
Receptor
Affinity: the extent to which a drug binds.
Efficacy: the extent to which a drug activates.
Nearly all drugs influence dopamine & norepinephrine
- Nucleus accumbens
= central to reinforcement and thus motivation for behavior
- Ventral tegmental area
= important dopamine pathway, dopamine is released as reward (connected to
nucleus accumbens) connected to frontal cortex
Craving:
Insistent search for drug (even after abstinence, may be triggered by cues). strong WANT
Drug paradox:
Reporting distress and aversion to drug but being unable to quit. (not LIKE, pure WANT)
Repeated exposure to drugs:
- hijacks reward system
= Satisfaction only through drugs, other reinforces are less satisfying.
- Disrupts prefrontal cortex
= cannot restrain impulse, use reasoning to restrain drug seeking impulse
strong effort to obtain drugs, addiction
- Neglect other things (quality of life) in order to pursuit drugs
- Withdrawal symptoms; physical dependence. (partly)
Combination of two withdrawals (psychological + physiological)
, Theories of addiction
- Physical dependence theory
= Addicted to drugs, because of fear of withdrawal symptoms
Criticism
Relapse after years without any withdrawal symptoms present
Addicts do not attribute relapse to withdrawal
Craving starts even before withdrawal symptoms arise
Curing withdrawal symptoms do not significantly improve treatment
- Positive incentive theory
Rewarding effects of drugs are responsible for addiction
Criticism
What biological factors are involved?
Why is not everyone addicted to drugs after taking it?
- Incentive sensitization theory
1. Craving
2. Reinstating craving after period of abstinence
3. Drugs become increasingly attractive
long-lasting neural sensitization of wanting (wanting-liking paradox)
This incentive salience takes place in the mesolimbic dopamine system
Positive incentive values – expected pleasure = HIGH(sensitization)
Hedonic value – actual pleasure = LOW (tolerance)
Addiction is also dependent on
- Social status; more resources to safer drugs, doctors, treatment, clinical conditions
- Stress; negative reinforcement
(Don’t relapse during withdrawal withdrawal stressful, starting after withdrawal
can reinforce an addiction)
- Environment; elevated craving in drug related environment.
- Ability to restrain from dangerous situations (willpower, self-direction)
ventromedial prefrontal cortex
As addiction develops enjoyable effects decrease higher dose for equal high.
Tolerance to a specific dose because:
Body learns how to counteract the effects of the drug
functional: receptors are less receptive to drug (less numerous)
metabolic: enzymes metabolize drug, less drug reaches target area
less communication between receptor and ion channels
Conditioned drug tolerance
Classical:
Situational specificity of drug tolerance
Drug related environment body prepares for drug (PHYSIOLOGICAL COMPENSATION)
tolerance to high doses (maximal tolerance in familiar/constant environment)
e.g., a lethal overdose is common in new context
Location/object can arouse craving/evoke pleasant feelings
Drug:
An exogeneous chemical, not necessary for normal cellular functioning, that significantly
alters the function of cells of the body when taken in relatively low doses.
Psychopharmacology:
Chemicals that affect nervous system (therapeutic or drugs of abuse)
Effect of drugs change physiological/behavioral processes
Common drugs are derived from plants (the chemicals that are present in plants)
Drugs can have various effects on NT’s
These effects may facilitate or inhibit the original (goal of the) NT.
Facilitate (mimic/increase NT or receptor) agonist
Inhibit (block NT/receptor antagonist
A drug is not either, but has mixed functions (e.g., it may facilitate 1 NT and inhibit another
OR, be an agonist for some doses but an antagonist for others)
Receptor
Affinity: the extent to which a drug binds.
Efficacy: the extent to which a drug activates.
Nearly all drugs influence dopamine & norepinephrine
- Nucleus accumbens
= central to reinforcement and thus motivation for behavior
- Ventral tegmental area
= important dopamine pathway, dopamine is released as reward (connected to
nucleus accumbens) connected to frontal cortex
Craving:
Insistent search for drug (even after abstinence, may be triggered by cues). strong WANT
Drug paradox:
Reporting distress and aversion to drug but being unable to quit. (not LIKE, pure WANT)
Repeated exposure to drugs:
- hijacks reward system
= Satisfaction only through drugs, other reinforces are less satisfying.
- Disrupts prefrontal cortex
= cannot restrain impulse, use reasoning to restrain drug seeking impulse
strong effort to obtain drugs, addiction
- Neglect other things (quality of life) in order to pursuit drugs
- Withdrawal symptoms; physical dependence. (partly)
Combination of two withdrawals (psychological + physiological)
, Theories of addiction
- Physical dependence theory
= Addicted to drugs, because of fear of withdrawal symptoms
Criticism
Relapse after years without any withdrawal symptoms present
Addicts do not attribute relapse to withdrawal
Craving starts even before withdrawal symptoms arise
Curing withdrawal symptoms do not significantly improve treatment
- Positive incentive theory
Rewarding effects of drugs are responsible for addiction
Criticism
What biological factors are involved?
Why is not everyone addicted to drugs after taking it?
- Incentive sensitization theory
1. Craving
2. Reinstating craving after period of abstinence
3. Drugs become increasingly attractive
long-lasting neural sensitization of wanting (wanting-liking paradox)
This incentive salience takes place in the mesolimbic dopamine system
Positive incentive values – expected pleasure = HIGH(sensitization)
Hedonic value – actual pleasure = LOW (tolerance)
Addiction is also dependent on
- Social status; more resources to safer drugs, doctors, treatment, clinical conditions
- Stress; negative reinforcement
(Don’t relapse during withdrawal withdrawal stressful, starting after withdrawal
can reinforce an addiction)
- Environment; elevated craving in drug related environment.
- Ability to restrain from dangerous situations (willpower, self-direction)
ventromedial prefrontal cortex
As addiction develops enjoyable effects decrease higher dose for equal high.
Tolerance to a specific dose because:
Body learns how to counteract the effects of the drug
functional: receptors are less receptive to drug (less numerous)
metabolic: enzymes metabolize drug, less drug reaches target area
less communication between receptor and ion channels
Conditioned drug tolerance
Classical:
Situational specificity of drug tolerance
Drug related environment body prepares for drug (PHYSIOLOGICAL COMPENSATION)
tolerance to high doses (maximal tolerance in familiar/constant environment)
e.g., a lethal overdose is common in new context
Location/object can arouse craving/evoke pleasant feelings
