15.6 - Current Approaches to the Mechanisms of Addiction

Question 1

Explain the general process of developing the positive incentive theories of drug addiction (5 steps)

Answer 1

1. physical dependence theories failed to explain a lot of shit, leading to the introduction of positive incentive theories
2. positive incentive approach plus studies on dopamine and ICSS led to a focus on the mesocorticolimbic pathway and reward mechanisms
   3, also began with early research on drug tolerance and dependence
3. Moved ahead with the discovery that drug associated cures can elicit conditioned compensatory responses through Pavlovian mechanisms that these are largely responsible for functional tolerance
4. further prominence when researchers discovered that conditioned responses elicited by drug association cures were major factors in craving and relapse

Question 2

what are modern approaches to drug addiction increasing concerned with?

Answer 2

modelling he three stages involved in the development of addiction - initial drug taking, habitual drug taking and drug craving/repeated relapse

Question 3

why do people tend to take a drug initially?

Answer 3

1. peer pressure
2. price, availability
3. prior life experiences

Question 4

what has been shown to promote initial drug administration in rats

Answer 4

1. food restrictions
2. social stress
3. environmental stress

Question 5

what has been shown to attenuate initial drug administration in rats

Answer 5

1. environmental enrichment
2. social interaction
3. access to non drug reinforcers

Question 6

what are the two behavioural traits that are associated with rats self administering cocaine?
what human personality trait has this been likened to?

Answer 6

1. preference for sweetened water
2. more active in novel environments
   - novelty seeking in humans, which is associated with initial drug taking in humans

Question 7

what do we see if we view drugs as tools?

Answer 7

people first take drugs to determine if they are useful to them, and continue to use them if they prove to be so

Question 8

what are some examples of people using drugs as tools?

is this always the case?

Answer 8

1. caffeine, stimulants and nicotine to increase alter ness
2. alcohol in low doses - social interaction, sex, relieve stress, anxiety
3. cannabis - relieve stress, anxiety
4. medical conditions to self medicate - ppl with schizophrenia with often use nicotine to alleviate cognitive impairments and anhedonia
   - no, people do just use them for pleasure

Question 9

Is habitual drug use always an outcome of drug use itself?

Answer 9

no, people can often periodically use drugs for their hedonic effects without using them habitually

Question 10

what are the two ways that positive incentive theories off addiction fail to account for the transition from initial periodic drug use to habitual use?

Answer 10

1. can’t explain why some people make the switch while others dont
2. can’t explain why addicted individuals experience a big discrepancy between hedonic value (liking) and positive incentive value (wanting) of their drug

Question 11

what is the difference between a drugs hedonic and positive incentive values?

Answer 11

PI values are the anticipated pleasure associated with an action
hedonic value is the ammt of pleasure that is actually experienced

Question 12

what do addicted individuals often say about the positive incentive value and hedonic value of their drug of choice?

Answer 12

PI value is often much higher, they really want the drug, but dont actually get as much pleasure from it as they used to - they dont really like it anymore

Question 13

what theory emerged to make sense of the two problems the positive incentive theory couldn’t make sense of? (bonus points if you can recall the problems)

Answer 13

incentive-sensitization theory -PI value of addictive drugs increase with repeated use in addiction prone individuals, which renders them highly motivated to consume it

Question 14

what is extremely important to note about the Incentive-sensitization theory?

Answer 14

the pleasure of the drug has nothing to do with the craving, it is the PI value that drives addicts towards the drug.
Initially, it was the hedonic value, but it gets has been flattened by tolerance, whereas the PI is sensitized

Question 15

Are there different brain systems responsible for hedonic and positive-incentive value?

Answer 15

yes, the nucleus accumbens via he mesocorticolimbic pathway is associated with PI value, not hedonic

Question 16

what is an example of a study that shows the importance of the Nucleus accumbens in the positive-incentive value of a drug?

Answer 16

neutral stimuli that signal the impending delivery of a reward can trigger dopamine release in the NA

Question 17

Do we know what brain structures are responsible for the hedonic value of a drug?

Answer 17

Not really, but we know they only somewhat overlap with PI value, and that dopamine is less important than we once believed

Question 18

what functional brain changes have been observed in the transition from initial to habitual drug taking? (2)

Answer 18

1. the striatum of drug addicts responds differently to drugs and associated cues
   - striata control of drug taking is shifted from the nucleus accumbens (the ventral striatum) to the dorsal striatum, an area known to play a role in habit formation and retention
2. impairments in pfc, likely relating to loss of self-control accompanying addiction

Question 19

are the functional changes associated with the transition from initial to habitual drug taking a result of the transition?

Answer 19

No, these differences predispose people to transition

Question 20

what has there recently been a growing appreciation for in terms of drug addiction and behavioural problems?

Answer 20

addiction is a specific expression of the more general behavioural problem: the inability to refrain from a behaviour despite its adverse effect
- addicted individuals make poor decisions engage in excessive risk taking, and have deficits in self control

Question 21

what is another important change in the affect of drug users?

Answer 21

anhedonia, which persists even after drug consumption ends making drug addiction a very difficult thing to overcome

Question 22

why is understanding the causes of relapse important in understanding addiction and its treatment?

Answer 22

even if people stop taking drugs or reduce quite bit through a program, they often. will have drug cravings weeks, months or even years later which can lead to. a. relapse - relapse after a long period of voluntary abstinence is a hallmark of addiction

Question 23

what are the three identified causes of relapse in addicted individuals

Answer 23

1. Stress - ex post 9/11 new Yorkers started using alcohol, cigarettes and marijuana a shit ton more
2. Drug priming - ppl who manage to abstain for years sometimes feel that they have it under control, only o try it again and immediately become full addicts again
3. Exposure to drug cues - people, places, objects associated with drug taking precipitates relapse
   - ex all the US soldiers who easily quit heroin after coming back from Nam is probably bc the environment changed

Question 24

Why do we think drug cues precipitate relapse

Answer 24

conditioned compensatory responses seem to increase cravings in abstaining people, just thinking about a drug can do this

Question 25

explain the incubation of drug craving

Answer 25

the fact that exposure to drug cues after drug withdrawal are less likely to elicit craving and relapse than cues presented later

Question 26

what drugs have we demonstrated the incubation of drug cravings in in rats?

Answer 26

blow, heroin, meth, booze and nicotine

Question 27

what does the incubation of drug craving help us explain?

Answer 27

why some people will have cravings triggered by an environmental cue after years of abstinence and relapse

Question 28

what two features has the animal literature on drug self administration suggested?
what does this lead the authors to conclude?

Answer 28

1. environmental enrichment after withdrawal has reduced cue and stress induced, but NOT priming induced relapse of drug self administration
2. Even a few brief exposures to non drug reinforcers reduce relapse of cocaine self administration
   - perhaps the best way to prevent relapse is to improve opportunities and surroundings. such interventions have in fact proven successful

Question 29

what has the criticism of the unatural housing and testing conditions in rats demonstrated
give an example

Answer 29

those rats who are group housed, access enriched environments, provided with non drug reinforcers, and housed in large naturalistic environments are much less likely to self administer drugs
- when given the choice between consuming sucrose and self administering cocainne, only 10% of rats prefer the coke

Question 30

what has the finding that more naturalistic housing ad testing conditions led to, in terms of criticisms and clinical implications?

Answer 30

1. critique - how generalizable are the studies to humans living inn the real world, who aren’t alone in cages?
2. clinical - drug addicts tend to have poor environments, so maybe given those most susceptible access to better environments and life choices will help

Question 31

what assumption led to the heightened focus on stimulants in the literature?

Answer 31

the idea that the mechanism of addiction is general - all drugs and all things cause addiction I the same way

Question 32

what two conclusions has the research on self administration of stimulants led to, and how have studies on opioids yielded different results?

Answer 32

1. all addictive drugs activate the mesocorticolimbic pathway
2. dopamine is important for the reinforcing properties of all addictive drugs
   - heroine self administration is not disrupted by mesocroticolimbic pathway lesions like cocaine is, potentially pointing to a different system of activity

Question 33

what are the two important features of Freud’s struggle with addiction?

Answer 33

1. everyone is susceptible to addiction no matter how smart or wjhhaterver
2. comparisons between two addictive drugs which freud had problems with