Addiction: Biological Explanation Flashcards

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1
Q

What are the Biological Explanations of Addiction?

A
  1. The Role of Dopamine

2. Genetic Factor

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2
Q

Describe the Mesolmibic (Reward) Pathway.

A
  • 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)
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3
Q

Why is Tolerance Experienced?

A
  • Dopamine receptors become less sensitive

- Causes a decrease in D2 receptors = decrease in dopamine released

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4
Q

Explain the Correlation Between Tolerance and Withdrawal

A
  • 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
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5
Q

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

A
  • 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.
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6
Q

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

A
  • 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.
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7
Q

The Role of Dopamine Evaluation

Not All Addictive Behaviors

A
  • 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
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8
Q

The Role of Dopamine Evaluation

The Complexity of the Role of Dopamine

A
  • 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
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9
Q

The Role of Dopamine Evaluation

Methodology Issues

A
  • 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
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10
Q

The Role of Dopamine Evaluation

Use of Non-Human Animal Studies

A
  • 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
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11
Q

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

A
  • 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.
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12
Q

What Genes are Associated with Addictions?

A
  1. DRD2

2. ADH Gene

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13
Q

What does DRD2 mean?

A
  • D2 Dopamine Receptor Gene
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14
Q

How is DRD2 Associated with Addictions?

A
  • 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.
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15
Q

What does ADH and ALDH mean?

A
  • ADH = Alcohol Dehydrogenase

- ALDH = Acetaldehyde Dehydrogenase

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16
Q

Describe the Breakdown of Alcohol

A
Alcohol
                          |
                          | Broken down by ADH
                          |
                  Acetaldehyde 
                          |
                          | Broken down by ALDH
                        /   \
                      /       \
    Acelic Acid         Water
17
Q

How is ADH Associated with Addictions?

A
  • 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
Q

What was the Diathesis- Stress Model?

A
  • Suggests that addictions occur when a genetic predisposition to the disorder is triggered by an environmental stressor.
19
Q

Genetic Factor Evaluation

Difference Between Imitation + Maintenance

A
  • 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
Q

Genetic Factor Evaluation

Genes for Addiction?

A
  • 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
Q

Genetic Factor Evaluation

Social + Cultural Factors

A
  • 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
Q

Genetic Factor Evaluation

Determinism

A
  • 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
Q

Genetic Factor Evaluation

Rejection of Disease

A
  • 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