PSYC 2920 Lecture 7 Dependence, Addiction and the Self-Administration of Drugs History of Addiction Research Addiction as a Disease Addiction as a Disease

PSYC 2920PSYC 2920

Lecture 7Lecture 7

Dependence, Addiction and theDependence, Addiction and theSelf-Administration of DrugsSelf-Administration of Drugs

History of Addiction ResearchHistory of Addiction Research Addiction as a DiseaseAddiction as a Disease

DSM IVDSM IV disease = disorderdisease = disorder Gives substance abuse the status of “diseases”Gives substance abuse the status of “diseases”

What are the practical consequences of labeling What are the practical consequences of labeling something as a disease?something as a disease?

FundingFunding Public perceptionPublic perception


History of Addiction ResearchHistory of Addiction Research PredispositionPredisposition

Either born or predisposed to drug abuseEither born or predisposed to drug abuse E.M. JellinekE.M. Jellinek The Disease Concept of AlcoholismThe Disease Concept of Alcoholism Alcoholics AnonymousAlcoholics Anonymous

Drug ExposureDrug ExposureAddition is caused by exposureAddition is caused by exposure

Is Addiction a DiseaseIs Addiction a Disease

AddictionAddiction

DSM-IVDSM-IV Substance Dependence: A maladaptive Substance Dependence: A maladaptive

pattern of substance use, leading to clinically pattern of substance use, leading to clinically significant impairment or distress, as significant impairment or distress, as manifested by three or more of the following manifested by three or more of the following within the same 12-month period…within the same 12-month period…

DSM-IV Criteria for Substance DependenceDSM-IV Criteria for Substance Dependence

ToleranceToleranceWithdrawalWithdrawalSubstance taken in larger amounts or over longer period than Substance taken in larger amounts or over longer period than intendedintendedPersistent desire or unsuccessful efforts cut down or control usePersistent desire or unsuccessful efforts cut down or control useGreat deal of time is spent in activities necessary to obtain the Great deal of time is spent in activities necessary to obtain the substance or recover from its effectssubstance or recover from its effectsImportant social, occupational, or recreational activities are given up Important social, occupational, or recreational activities are given up or reduced because of useor reduced because of useThe substance use is continued despite knowledge of having a The substance use is continued despite knowledge of having a persistent or recurrent physical or psychological problem that is persistent or recurrent physical or psychological problem that is likely to have been caused or exacerbated by the substancelikely to have been caused or exacerbated by the substance

DSM-IV Criteria for Substance AbuseDSM-IV Criteria for Substance Abuse

A. A maladaptive pattern of substance use leading to clinically significant A. A maladaptive pattern of substance use leading to clinically significant impairment or distress, as manifested by one (or more) of the following, impairment or distress, as manifested by one (or more) of the following, occurring within a 12-month period: occurring within a 12-month period:

Recurrent substance use resulting in a failure to fulfill major role obligations at Recurrent substance use resulting in a failure to fulfill major role obligations at work, school, or home (e.g., repeated absences or poor work performance work, school, or home (e.g., repeated absences or poor work performance related to substance use; substance-related absences, suspensions or related to substance use; substance-related absences, suspensions or expulsions from school; neglect of children or household) expulsions from school; neglect of children or household)

Recurrent substance use in situations in which it is physically hazardous (e.g., Recurrent substance use in situations in which it is physically hazardous (e.g., driving an automobile or operating a machine when impaired by substance use) driving an automobile or operating a machine when impaired by substance use)

Recurrent substance-related legal problems (e.g., arrests for substance-related Recurrent substance-related legal problems (e.g., arrests for substance-related disorderly conduct) disorderly conduct)

Continued substance use despite having persistent or recurrent social or Continued substance use despite having persistent or recurrent social or interpersonal problems caused or exacerbated by the effects of the substance interpersonal problems caused or exacerbated by the effects of the substance (e.g., arguments with spouse about consequences of intoxication, physical fights) (e.g., arguments with spouse about consequences of intoxication, physical fights)

B. The symptoms have never met the criteria for Substance Dependence for B. The symptoms have never met the criteria for Substance Dependence for this class of substance. this class of substance.


Addiction as Physical DependenceAddiction as Physical Dependence BackgroundBackground

Withdrawal or Abstinence SyndromeWithdrawal or Abstinence SyndromePhysical or Physiological DependencePhysical or Physiological DependenceDependenceDependenceToleranceTolerance

Habituation Habituation Condition in which the user desires a drug, but Condition in which the user desires a drug, but suffers not ill effects on its discontinuancesuffers not ill effects on its discontinuance

The term “habituation” is no longer commonly used in The term “habituation” is no longer commonly used in this way.this way.

Psychological DependencePsychological DependenceCircular DefinitionCircular Definition


Addiction as Physical DependenceAddiction as Physical Dependence Problems with the Physical and Psychological Problems with the Physical and Psychological

Dependence TheoriesDependence TheoriesNot all develop physical dependenceNot all develop physical dependence

Some will voluntarily stop taking a drug even with Some will voluntarily stop taking a drug even with the presence of withdrawal symptomsthe presence of withdrawal symptoms

Psychological dependence is circular in reasoningPsychological dependence is circular in reasoning


Modern Behavioral and Neuroscientific Modern Behavioral and Neuroscientific ExplanationsExplanations BackgroundBackground

Flavor toxicosis learningFlavor toxicosis learning Animals won’t do drugs if they taste badAnimals won’t do drugs if they taste bad Only human can become addicted (disproven)Only human can become addicted (disproven)

Positive reinforcement modelPositive reinforcement model Positive reinforcer is any stimulus that increases the Positive reinforcer is any stimulus that increases the

frequency of a behavior it is contingent on.frequency of a behavior it is contingent on.


Drug Self-Administration in AnimalsDrug Self-Administration in Animals


Drugs as Positive and Negative Drugs as Positive and Negative ReinforcersReinforcers Self-Administration via Other RoutesSelf-Administration via Other Routes

IntragastricIntragastric

IntracranialIntracranial

IntraventricularIntraventricular

InhalationInhalation Drugs as Aversive StimuliDrugs as Aversive Stimuli

Not all drugs have positive reinforcersNot all drugs have positive reinforcers

LSD in animalsLSD in animals


Self-AdministrationSelf-Administration

• The similarity between The similarity between the patterns of self-the patterns of self-administration of ethanol administration of ethanol in a human and a rhesus in a human and a rhesus monkey under continuous monkey under continuous drug availability. The drug availability. The arrows indicate the arrows indicate the occurrence of withdrawal occurrence of withdrawal symptoms.symptoms.


Drugs as Positive and Negative Drugs as Positive and Negative ReinforcersReinforcers Problems with the Positive Reinforcement Problems with the Positive Reinforcement

ModelModelDiscounting delayDiscounting delay

CircularityCircularity


Self-Administration in Humans and Self-Administration in Humans and NonhumansNonhumans Mello & Mendelson (1987)Mello & Mendelson (1987)

Ethical?Ethical? Similarities and Differences Between Human Similarities and Differences Between Human

and Nonhuman Animalsand Nonhuman AnimalsNot a great deal of difference between speciesNot a great deal of difference between species

Type of drugType of drug Patterns of Self-AdministrationPatterns of Self-Administration

Why use animal models?Why use animal models?

Experimental controlExperimental control Can separate variables from each other more easilyCan separate variables from each other more easily

Reward and stress brain systems are common to many Reward and stress brain systems are common to many vertebrates, particularly mammalsvertebrates, particularly mammals

Major differences between humans and other mammals is with Major differences between humans and other mammals is with cortical and neocortical structurescortical and neocortical structures

More direct probing of structural and pharmacological More direct probing of structural and pharmacological contributions to drug-related behaviour can be contributions to drug-related behaviour can be conductedconducted

lesionslesions drug administrationdrug administration recordingrecording

Modeling addiction in non-human Modeling addiction in non-human speciesspecies

Must distinguish casual drug use from drug dependenceMust distinguish casual drug use from drug dependence

Successful models of dependence should mimic the Successful models of dependence should mimic the DSM-IV criteria for drug dependenceDSM-IV criteria for drug dependence

Compulsion to seek and take the drugCompulsion to seek and take the drug

Loss of control in limiting intakeLoss of control in limiting intake

Emergence of negative emotional state (e.g., dysphoria, anxiety, Emergence of negative emotional state (e.g., dysphoria, anxiety, tability) when access to the drug is preventedtability) when access to the drug is prevented


Measuring the Reinforcing Value of DrugsMeasuring the Reinforcing Value of Drugs Rate of RespondingRate of Responding Progressive RatioProgressive Ratio

Breaking pointBreaking point Organism will stop respondingOrganism will stop responding

ChoiceChoiceTwo levers; one has consequencesTwo levers; one has consequences

Place ConditioningPlace ConditioningAnimal will spend time in area of reinforcementAnimal will spend time in area of reinforcement

Conditioned place preferenceConditioned place preference

A model of drug-seeking behaviourA model of drug-seeking behaviour

Relies on classical rather than operant conditioningRelies on classical rather than operant conditioning Drug administration does not require a response from the animalDrug administration does not require a response from the animal

Procedure (unbiased version)Procedure (unbiased version) Preconditioning: days 1-3Preconditioning: days 1-3 Conditioning: days 4-7Conditioning: days 4-7 Test: day 5Test: day 5 State-dependent learning test: day 6 (often not done)State-dependent learning test: day 6 (often not done)

Strength of association depends on drug dose and number of Strength of association depends on drug dose and number of conditioning sessionsconditioning sessions

Conditioned place preferenceConditioned place preference


Factors That Alter the Reinforcing Value Factors That Alter the Reinforcing Value of Drugsof Drugs Reinforcing Value of Different DrugsReinforcing Value of Different Drugs

Abuse potentialAbuse potential

Abuse liabilityAbuse liability Dose of DrugDose of Drug Genetic DifferencesGenetic Differences Relief of Unpleasant SymptomsRelief of Unpleasant Symptoms Task DemandsTask Demands StressStress

Social stress findings:Social stress findings:AmphetamineAmphetamine

•Social stress: • starting on day 30, daily

1-hr isolation in a round, ventilated plastic container (approx. 10 cm diameter and 10 cm high)

• After isolation, rats were returned to the colony and housed each day with a new cage partner that was also undergoing the stress procedure.

• on Day 45, rats were housed with their original cage partner. maintenance.

CPP stress findingsCPP stress findings

Fewer conditioning sessions required for Fewer conditioning sessions required for cocaine-seeking behaviour in conditioned place cocaine-seeking behaviour in conditioned place preference model in rats that are rearedpreference model in rats that are reared alone vs. in groupsalone vs. in groups in impoverished environments vs. with toysin impoverished environments vs. with toys

Rightward shift in amphetamine dose response Rightward shift in amphetamine dose response (indicative of tolerance) in rats where dams have (indicative of tolerance) in rats where dams have been exposed to stressbeen exposed to stress

GeneticsGenetics

• Strains of rats bred to mimic human alcohol-dependent individuals

• Marchigian Sardinian alcohol-preferring (msP) rats

• Some evidence that genetic differences in humans contribute to alcohol dependence

• Related to breakdown of metabolic products of alcohol

• May be rooted in historical calorie hoarding (i.e. agrarian vs. hunter gatherer societies

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PSYC 2920 Lecture 7 Dependence, Addiction and the Self-Administration of Drugs History of Addiction Research Addiction as a Disease Addiction as a Disease