dependence and addiction!! psychology 3506. introduction when people first thought about it (and...
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IntroductionIntroduction
When people first thought about it When people first thought about it (and until relatively recently) drug (and until relatively recently) drug taking behaviour just seemed oddtaking behaviour just seemed odd• Not avoiding painNot avoiding pain• Doesn’t affect all people the same wayDoesn’t affect all people the same way• You don’t ‘need’ itYou don’t ‘need’ it
Aha! You must be an immoral pig, Aha! You must be an immoral pig, probably with little willpower. You probably with little willpower. You are a bad person you junkie lowlifeare a bad person you junkie lowlife
The Disease ModelThe Disease Model
Oh perhaps it is not a problem with Oh perhaps it is not a problem with your character or moralityyour character or morality
Ahh, yes, it is a diseaseAhh, yes, it is a disease• Or a disorder as we say todayOr a disorder as we say today
Started with alcoholismStarted with alcoholism What is the disease mechanism?What is the disease mechanism? But it is genetic!But it is genetic!
• So whatSo what
Physical Dependence ModelPhysical Dependence Model
Withdrawal (from morphine) caused Withdrawal (from morphine) caused by ‘autotoxin’by ‘autotoxin’
Found to be lacking, but, the idea Found to be lacking, but, the idea stuck. stuck.
Indeed, still VERY popular Indeed, still VERY popular Accounts for the ‘abnormality’ of it allAccounts for the ‘abnormality’ of it all Can be combined with the disease Can be combined with the disease
modelmodel
Physical Dependence ModelPhysical Dependence Model
Only Depressants?Only Depressants?• Tatum and Seevers (1931) added Tatum and Seevers (1931) added
habituationhabituation Problem is, that stimulants, for the Problem is, that stimulants, for the
most part, don’t produce withdrawal most part, don’t produce withdrawal symptomssymptoms
Hmm, Let’s invent a new idea!Hmm, Let’s invent a new idea!
Psychological DependencePsychological Dependence
When you need a drug, but don’t When you need a drug, but don’t need a drugneed a drug
When you crave a drugWhen you crave a drug• CircularCircular
Biggest problems:Biggest problems:• Continual abuse with drugs that do NOT Continual abuse with drugs that do NOT
produce withdrawalproduce withdrawal• Addiction without dependenceAddiction without dependence
Positive Reinforcement ModelPositive Reinforcement Model
People used to think you couldn’t get People used to think you couldn’t get animals addictedanimals addicted• Not moralNot moral• Can’t get the diseaseCan’t get the disease
CatheterCatheter Work for drugWork for drug
• (Thompson and Shuster, 1964)(Thompson and Shuster, 1964)
How does it work?How does it work?
Seems circular, until you realize that Seems circular, until you realize that we know what a reinforcer is not just we know what a reinforcer is not just from operational definition, but from from operational definition, but from physiologyphysiology
Dopamine hypothesisDopamine hypothesis• VTA -> MFB -> ACCVTA -> MFB -> ACC
Morphine to PVG leads to Morphine to PVG leads to dependence, to ACC, does not!dependence, to ACC, does not!
Animals and us aren’t so different Animals and us aren’t so different after all….after all….
Shuster’s other workShuster’s other work• Rats will work for drugs not causing withdrawalRats will work for drugs not causing withdrawal• Rats will work for drugs without dependence!Rats will work for drugs without dependence!
Is hard to get them to take things orally Is hard to get them to take things orally thoughthough
Pickens and Thompson (1968) found that Pickens and Thompson (1968) found that drug use follows the laws of learning!drug use follows the laws of learning!
So you are saying it is just So you are saying it is just conditioning?conditioning?
Well, umm YesWell, umm Yes Explains the paradox of positive and Explains the paradox of positive and
negative effects of drugsnegative effects of drugs Choice in taking a drug depends on Choice in taking a drug depends on
other available reinforcersother available reinforcers• Hayman says it follows the matching Hayman says it follows the matching
law!law!
Behavioural EconomicsBehavioural Economics
Basically applying the ‘laws’ of Basically applying the ‘laws’ of economics to behaivoureconomics to behaivour
Elasticity of demand is a biggieElasticity of demand is a biggie Caroll’s (1993) data on PCPCaroll’s (1993) data on PCP
• Demand changed from elastic to Demand changed from elastic to inelastic, depending on price. inelastic, depending on price.
• Inelastic at low pricesInelastic at low prices
Carroll (1993)Carroll (1993)
Different prices Different prices (number of responses) (number of responses) for drugfor drug
Demand inelastic, Demand inelastic, until it gets expensiveuntil it gets expensive
If there is something If there is something else available else available (saccharin in this (saccharin in this case) the monkeys will case) the monkeys will switch to it switch to it (substitution)(substitution)
ConclusionsConclusions
Drug taking behaviour can be easily Drug taking behaviour can be easily modeled using animalsmodeled using animals• We all follow the laws of learningWe all follow the laws of learning
Not all drugs will be self administered Not all drugs will be self administered by all animals, so be carefulby all animals, so be careful