A contemporary perspective on drug

abuse

Terry Bazzett

Department of Psychology

SUNY Geneseo

Reinforcement as a Biological Concept

Why do people abuse drugs? Drug abuse seems counterintuitive.

Health problemsSocial problemsRelationship problemsFinancial problems

From a biological perspective it is intuitive.Our brains reinforce useful behaviorsThe brain does not distinguish between useful

behaviors and drug use.

Neural pathways control behaviors The nigrostriatal pathway controls movement

Neural pathways control behaviors The mesolimbic pathway reinforces behavior

Neural pathways reinforce behaviors The mesolimbic pathway is “designed” to

Reinforce useful behaviorsReinforce naturally occurring behaviorsThis is a perfectly good design

Useful behaviors can be bypassedUsing electrical stimulationUsing drugsThis is abuse of a perfectly good design

Dopamine… a common denominator The mesolimbic pathway uses dopamine (DA)

Drugs of abuse typically stimulate DA pathwaysIn general, reinforcement is correlated with DA activityDrugs that inhibit DA are not pleasurable

Secondary effects

While DA reinforcement is the primary driving force for drug use, other effects contribute.Depressants for those who are anxiousStimulants for those who want greater arousalHallucinogens for those who want altered experiencesOpiates for those who want sedationEtc.

Drug abuse as a Biological Concept

Why not enjoy drugs?

If drugs stimulate a natural system, what’s the harm in enjoying them?For occasional recreational use, probably nothing.When use becomes heavy or persistent, problems

may arise.○ Drugs are generally more potent than natural

reinforcers ○ Drugs are “easier” than natural reinforcers○ The reinforcement pathway may down-regulate.

What is down-regulation

Biological systems strive for homeostasis When systems are highly active, the body

responds by decreasing activity. Down-regulation is part of the biological

basis for drug tolerance (habituation)

What is down-regulation

What is down-regulation

Decrease in transmitter release (rapid) Decrease in receptor sensitivity (slower) Decrease in receptor sites (slower)

The down side of down-regulation Once down regulation occurs, a vicious cycle begins.

More drug is required to feel intoxicationMore drug use results in greater down-regulation

A down-regulated reinforcement circuit meansIncreases in drug are neededPleasure in natural reinforcers is decreased

Double your pleasure, double your fun

Compensating for down-regulation

When a system becomes less responsive:You can increase your drug doseCombine drugs to potentiate effectsCombine drug with arousing behavior (e.g. sex)

Each of these has its own risks

Increasing drug dose

Primary risk of overdoseSecondary economical problemsSecondary side-effect problems

Combining drugs

Sometimes used to potentiate DA while also compensating for secondary effects Speedball as example of a deadly combinationMany other combinations may be used

Combining drugs and sex

Combining a DA releasing behavior with a DA stimulating drug potentiates effectsMany drugs impair cognitive function, leading to

risky sex behavior

Pick your poison… the classics

Alcohol

The misnomer of “drugs and alcohol”.Alcohol is a drug

○ Highly addictive○ Extremely potent○ Deadly… overdose, accidents, combined with

other drugs○ Deadly… withdrawal

Alcohol – Biology

Indirectly enhances DA systems Alcohol enhances GABA activity Increased GABA activity = relaxation

Most anti-anxiety drugs also increase GABAMany people self-medicate with alcohol

GABA down-regulation Results in anxiety in the absence of alcoholIn extreme cases withdraw = seizures/death

Alcohol – the great social stimulant The cortex actively inhibits impulsive behavior

GABA activation inhibits this inhibitionAlcohol reduces ability to control impulsive

behaviorImpulsive behaviors

○ Driving while drunk○ Unprotected sex○ Consuming additional drugs (including alcohol)

Alcohol – treating addiction

Down regulated GABA treated with benzodiazapines (anti-anxiety meds).

Down regulated DA system may require antidepressant drugs

Cold turkey is ill-advised

Pick your poison… the classics

Stimulants

Includes cocaine, amphetamine, Ritalin, etcHighly addictiveHighly reinforcingIntense cravingsRelatively mild physical withdrawal

Stimulants – Biology

Directly enhance DA activity Also increase norepinephrine (NE) =

excitationIncreased NE = awake and alertSome people self-medicate with stimulantsMost people use stimulants to enhance the party

DA and NE down-regulation Results in depression/lethargy when drug not usedThese symptoms increase craving/desire for drug

Stimulants – treating addiction Down regulated DA system may require

antidepressant drugs Lethargy has to be waited out Cold turkey is difficult because of cravings, but

not typically dangerous

Pick your poison… the classics

Opiates

Includes morphine, codeine, heroin, oxycodone, suboxone (buprenorphine), etc. etc. etc.Highly addictiveHighly reinforcingHigh cravingsModerate physical withdrawal

Opiates: Not just a “street drug”

“I am addicted to prescription pain medication.” -- Rush Limbaugh show, Oct 10, 2003

"If (Surgeon General Jocelyn Elders) wants to legalize drugs, send the people who want to do drugs to London and Zurich, and let's be rid of them. -- Rush Limbaugh show, Dec 9, 1993

Opiates – Biology

Indirectly enhances DA systems Directly enhance endogenous opiate systems

SedationExtreme analgesiaSome claim reduction of “emotional pain”

DA and opiate down-regulation Results in depression/pain when drug not usedThese symptoms increase craving/desire for drug

Opiates– treating addiction

Down regulated DA system may require antidepressant drugs

Opiate withdrawal can be tempered with methadone Methadone is another opiate system stimulantMethadone treatment creates it’s own problems

Cold turkey is difficult because of cravings, but not typically dangerous

Pick your poison… the classics

Marijuana

Smoked or ingested orallyNot particularly addictiveNot particularly reinforcingRelatively mild cravingsMild physical withdrawal

Marijuana – Biology

Indirectly enhances DA activity Directly stimulates cannabinoid receptors

Anandamide is our “endogenous marijuana”Functions are unknown… guesses?

DA and Cannabinoid down-regulation Mild depression/anxiety when drug not usedThese symptoms increase desire for drug

Marijuana – treating addiction Down regulated DA system may require

antidepressant drugs Anti-anxiety drugs may be prescribed Cold turkey is typical for this drug

When good mice go bad.

Visit the mouse party for fun information

Pick your poison… the new wave

MDMA – Ecstasy

3,4-methylenedioxy-N-methylamphetamineIncreases serotonin, DA, and NE releaseConsidered a stimulant

But… many variations existLack of control in manufacturingamphetamine, methamphetamine, ephedrine,

caffeine, are all cheaper substitutes

MDMA – Biology

Comparatively little known about dependenceWithdrawal often accompanied by dysphoria

Studies indicate neurotoxic effectsSerotonin and DA neurons degenerate in animalsToo soon to know about long-term human effectsSome concern about early life sub-threshold loss

Pick your poison… the new wave

MEPH/MDPV – Bath Salts

Key ingredientsMEPH (Mephedrone) MDPV (methylenedioxypyrovalerone)

But… as with MDMA Cheaper variations may existAll components likely to have stimulant effects

MEPH/MDPV – Biology

MEPHEnhances release of DAMay enhance release of other transmitters

MDPVBlocks re-uptake (deactivation) of transmitter after

it has been releasedThis is an effect similar to cocaineAgitation, anxiety, overdose can cause death

Pick your poison… the new wave

Salvia Divinorum

Currently not illegal Little research exists on effects

Addictive potential seems lowLittle or no effect on brain DA (?)

Concerns over use still exist

Salvia smoking video

Salvia Divinorum - Biology

Binds to opioid receptor sites Response similar to serotonin hallucinogens

Spice/K2 – synthetic cannabis Currently not illegal Herbs mixed with synthetic cannabinoids

Synthetic cannabinoids have unknown effects

Concerns over useCan trigger psychosis in predisposed individualsPredisposed individuals are most inclined to useMyocardial Infarction has been reported in several

young healthy users

Spice/K2 - Biology

Binds to cannabinoid receptor sites Very little is known beyond this…

Pick your poison… the new wave

Alkyl nitrites – Poppers

Very little research…Considered to have stimulant effectsSome analgesic properties?Some ability to relax striated muscles?

Variants are used to treat anginaAmyl nitrite… similar compound, similar effects

Little (no) addictive potential

Alkyl nitrites – Biology

Blood vessel dilation, increased heart rateBrain effects are unclear

Retinal toxicity has also been reportedUsers need to be aware of possible damage to

visual system

Theories of Addiction

“Just say no”… a flawed campaign

It’s easy to say “no” when you’re…In your 60sMarried to the President of the United StatesA millionaire

Reasons to say “yes” to drugs When natural reinforcement is hard to come by

Drugs are cheap Drugs require little effortSocial acceptance may come with drug useDrugs can make you feel like a millionaire married

to the President of the United States.

Swansea Love Story (loud)

What is drug addiction?

Currently debatedCravings more than physical dependenceTendency to relapseContinued use in the face of harm

No “typical” progressionBut certain stages are commonSome progressions paths are likely/unlikelySome users may “mature out”

8.4 The continuum of drug use

Models of Addiction Physical Dependence model

Drugs thwart withdrawal symptoms

Positive Reinforcement modelLike bar pressing rat… we learn drugs=euphoriaLearned behavior persists with down-regulation

Liking and Wanting modelOne brain system “likes” drugs (reinforcement)

and down-regulatesOne brain system “wants” drugs (?) and does

not down-regulate

Models of Addiction Disease model

Some physiological susceptibilitySusceptibility worsens with repeated exposureThere are possible genetic factors

Biopscyosocial modelIt is difficult to deny any of these factors as

possible contributorsThis is the most comprehensive model