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Flashcards in Addiction: Biological Explanation Deck (23):
1

What are the Biological Explanations of Addiction?

1. The Role of Dopamine
2. Genetic Factor

2

Describe the Mesolmibic (Reward) Pathway.

- Evolved in humans to be adapted response to behaviors that are good for us e.g. eating
- Release of dopamine can be triggered by behavior (e.g. gambling) or a substance (e.g. alcohol)

Addictive Behavior/Substance
|
| Release of Dopamine
|
Vental Tegmental Area (VTA)
|
| Sense of Pleasure
|
Nucleus Accumbens (NAC)

3

Why is Tolerance Experienced?

- Dopamine receptors become less sensitive
- Causes a decrease in D2 receptors = decrease in dopamine released

4

Explain the Correlation Between Tolerance and Withdrawal

- Addict will need to engage in more addiction to experience same effects + avoid withdrawal symptoms
- Engaging in behavior becomes more about avoiding withdrawal symptoms rather than experiencing initial pleasure

5

What Role does the Frontal Cortex Play in Maintaining the Addiction?

- Linked higher cognitive functions (e.g. decision making + memory)
- Addictive behavior changes brain circuits that decide what to pay attention to - too much importance (salience) to behaviors/cues associated with addiction.
- Dopamine system makes individual want to engage in behavior rather than like it - many addicts report that they no longer enjoy the experience but cannot overcome the cravings.

6

What has Research Found Regarding to the Role of the Frontal Cortex and Maintaining the Addiction?

- Research evidence with cocaine addicts
- Volkow = abnormalities in frontal cortex
- Bolla = impaired performance frontal cortex task
- Wang = increase activity in frontal cortex when exposed to addictive behavior.

7

The Role of Dopamine Evaluation
Not All Addictive Behaviors

- NEGATIVE
- Evidence to show that dopamine increase following drug consumption is not always the case
- Stokes (2009) = No significant increase in cannabis users
- Yoder (2007) = No consistent increase in dopamine when given alcohol
- Not appropriate to say that dopamine explains all addiction

8

The Role of Dopamine Evaluation
The Complexity of the Role of Dopamine

- NEGATIVE
- Dopamine has a range of other functions
- Bell (2013) = dopamine is the Kim Kardasion of Neurotransmitters - fashionable to blame dopamine for causing a range of problems
- Dopamine levels increase in presence of aversive stimuli - helps us to avoid situations
Liberzon (1999) = increased activation in NAC in veterans suffering from PTSD when reminded of battles through combat sounds
- Doesn't match the idea of this area being simply about pleasure

9

The Role of Dopamine Evaluation
Methodology Issues

- NEGATIVE
- Nutt (2015) = criticized the methodology used by researchers in this area
- Samples were small + participants given substance to measure its effects - often in a different form
- Given in a lab rather than usual environment
- measured effects are not always accurate

10

The Role of Dopamine Evaluation
Use of Non-Human Animal Studies

- NEGATIVE
- Studies may not give true insight into how humans become addicted
- Misses social context in which addictions take place - cannot replicate same behaviors of addiction
- However, does allow researcher to study the effects of drugs in ways that aren't possible with humans

11

How is the Role of Dopamine Applied to modify addiction? (Using Varenicline)

- Addiction linked to the pleasure an individual feels as a result of dopamine being released
- By reducing the dopamine being released could hep to diminish cravings for the addictive behavior
- Varenicline (champix) is a prescribed drug to help people stop smoking
- Varenicline binds to nicotine receptors, tricking brain into thinking it's had nicotine - leads to a small release of dopamine
- Also reduces rewarding effects of nicotine by blocking nicotine's ability to access the receptor + activate release - if person smokes a cigarette person will get pleasure from it
- Drug has proved the be successful - provide extra support for the role of dopamine in addiction - However most effective when used alongside other methods.

12

What Genes are Associated with Addictions?

1. DRD2
2. ADH Gene

13

What does DRD2 mean?

- D2 Dopamine Receptor Gene

14

How is DRD2 Associated with Addictions?

- Individuals with A1 varient of gene have fewer dopamine receptors in the area of the brain which provides us with sense of pleasure to normal adaptive behavior (e.g. sex + food)
- lower numbers of dopamine receptors leads individual to compensate for this over stimulation through engaging in addictive behavior
- Comings (1996) = 48.7% smokers carried A1 variant compared with 25.9% of general population
- Gambling Addictions = 50.9% of addicts carried A1 variant compared with 25.9% of non-addicts.

15

What does ADH and ALDH mean?

- ADH = Alcohol Dehydrogenase
- ALDH = Acetaldehyde Dehydrogenase

16

Describe the Breakdown of Alcohol

Alcohol
|
| Broken down by ADH
|
Acetaldehyde
|
| Broken down by ALDH
/ \
/ \
Acelic Acid Water

17

How is ADH Associated with Addictions?

- Some variants of ALDH + ADH gene decreases risk of alcoholism by increasing acetaldehyde - causes unpleasant reactions to alcohol (e.g. Nausea)
- Mainly found in East Asians populations - help to explain lower rates of alcoholism in these cultures
- Variants of ADH may break down alcohol at a slower rate - likely to drink more + become addicted

18

What was the Diathesis- Stress Model?

- Suggests that addictions occur when a genetic predisposition to the disorder is triggered by an environmental stressor.

19

Genetic Factor Evaluation
Difference Between Imitation + Maintenance

- POSITIVE
- Twin studies used to demonstrate the influence of genetic factors in addiction
- Kendler + Prescott = interviewed 2000 twins - found social + environmental factors influence a person's cocaine use - however whether person becomes addicted more dependent on genetic factor
- Concordance rates for cocaine initiation -
MZ= 54% DZ=42%
- Concordance rates with cocaine dependence -
MZ = 35% DZ=0%

20

Genetic Factor Evaluation
Genes for Addiction?

- NEGATIVE
- Relationship between genetics + addiction is very complex
- Ojelade (2015) = RSU1 not functioning properly in fruit flies - lower sensitivity to alcohol
- Brain imaging used in humans to test for this - found a relationship between this and alcohol dependency
- The range of different genes identified means we cannot say that there is one gene for addiction
- Number of different types of addictive behaviors all of which may be triggered by different genetic mechanism

21

Genetic Factor Evaluation
Social + Cultural Factors

- NEGATIVE
- Kendler (2000) = heritabelity of tobacco changes over time
- Kendler completed a twin pair study between 1910-1958 - found that women born in the 1st 1/2 had little/no influence on the heriability - women born in the 2nd 1/2 had a heriability of 60%
- Boardman (2008) = twin + sibling study found a strong genetic component in smoking behaviors the rate for daily smoking varied across schools
- Herilability rate was highest in schools where the most poplar students smoke

22

Genetic Factor Evaluation
Determinism

- POSITIVE
- Only some people are likely to addictive
- Reduces amount of blame placed on addict - suggesting that they could not have controlled addiciton
- HOWEVER
- Individual sees addiction as an unstoppable consequence of their genetic makeup - less likely to take responsibility for their own recovery

23

Genetic Factor Evaluation
Rejection of Disease

- NEGATIVE
- Lewis (2015) = labeling addiction as a disease can damage addicts self essteam and make them feel helpless in overcoming their addiction
- Lewis also suggests to consider changes that happen in the brain as a form of learning