Explanation 2 - Addiction Genes

Question 1

what is this explanation

Answer 1

if genes play a part in development of addiction then people closely related should share the behaviour
David Goldman et al 2005 concluded that ‘ addictions were moderately to highly heritable’ and reported that heritability of addictions range from +39 for hallucinogens to +72 for cocaine

Question 2

David Goldman et al 2005

Answer 2

concluded that ‘ addictions were moderately to highly heritable’ and reported that heritability of addictions range from +39 for hallucinogens to +72 for cocaine

Question 3

genes associated with addiction

Answer 3

the role of D2 dopamine receptor gene (DRD2)
individuals with A1 variant of this gene have fewer dopamine receptors in an area of the pleasure that provides us with pleasure so overcompensation

Question 4

stats for genes associated with addiction

Answer 4

David Commings et al found that 48.7% of smokers and ex smokers carried the A1 variant compared with 25.9% general population

similar results found in gambling addicts where 50.9% had the A1 variant compared to 25.9% non addicts

Question 5

what genes are responsible for the process of how alcohol is metabolised

Answer 5

ADH and ALDH

Question 6

how does ADH genes metabolise alcohol

Answer 6

body metabolises alcohol into acetaldehyde due to an enzyme called alcohol dehydrogenase (ADH) then another enzyme called acetaldehyde dehydrogenase (ALDH) breaks it down further into acetic acid and water

Question 7

what do other variant of ADH genes cause

Answer 7

decrease risk of alcoholism by increasing acetaldehyde levels in the body. This in turn causes unpleasant reactions to alcohol, such as facial flushing and nausea.
This reaction is found in larger concentrations among East Asian populations and may help to explain the lower rates of alcoholism
– therefore individuals find the experience unpleasant so don’t do it again therefore don’t become addicted

Question 8

variations of this gene therefore have been linked to increased risk of alcoholism

Answer 8

individuals may break down alcohol at a much slower rate than others so more likely to drink more and become addicted

Question 9

lower activity variants of ADH gene

Answer 9

increased risk of alcohol dependence in oriental populations (huiguchi et al)

Question 10

ADH4 variants

Answer 10

have found to affect alcoholism risk in european populations (edenberg et al 2006)

Question 11

Diathesis Stress Model info

Answer 11

it is too simplistic to think addiction could be caused by biological factors such as genetics
* important to consider of genetic factors might interact with environment

Question 12

what does Diathesis stress model state

Answer 12

suggests that a disorder such as addiction only develops when a genetic predisposition to a particular disorder is triggered by an environmental stressor
EG serotonin transporter gene (5HTT) has also been linked to the development of alcoholism but not on its own - it appears to interact closely with environmental factors such as maltreatment in childhood ( kaufman et al)

Question 13

Evaluation of Biological Explanation 2 - Addiction genes

Answer 13

1. difference between initiation and maintenance
2. A ‘gene’ for addiction
3. determinism
4. role of social and cultural factors

Question 14

the difference between initiation and maintenance

Answer 14

*twin studies
kenneth kendler and carol prescott interviewed nearly 2000 twins and found that although environmental and social factors influenced whether a person would initiate cocaine use whether the person became addicted was more dependant on genetic factors

Question 15

concordance rates for cocaine initiation

Answer 15

MZ twins 54%
DZ twins 42%

Question 16

Concordance rates for cocaine dependence

Answer 16

substantial difference between mz and dz (35% and 0% respectively) suggesting a much greater role for genetic factors in addiction rather than the decision to use it

Question 17

A ‘gene’ for addiction info

Answer 17

relationship between gene and addiction more complex than appears.
* a range of different genes identified means we cannot simply say there is a gene for addiction
theres a number of diff addictions all of which may be triggered by other genetic mechanisms

Question 18

research for a gene for addiction

Answer 18

Shamsideen Ojelade et al found that when a gene called Rsu1 was not functioning correctly in fruit flies it would lower their sensitivity to alcohol.
brain imaging was used with humans to test for this and found a relationship between this and alcohol dependence

Question 19

Determinism

Answer 19

*Strength of biological explanations they explain why only some people go on to become addicted even though many people try these behaviours
- reduces amount of blame placed on addict themselves by taking a determinist view suggesting addict could not have controlled addiction.
bad - if individual sees addiction as unstoppable genetic makeup they may never take responsibility of their own recovery - responsibility which important to overcome their addiction

Question 20

Role of social and cultural factors

Answer 20

genetic explanations ignore other factors
Kenneth kendler et al showed that the heritability of tobacco changed over time. By studying swedish twin pairs born between 1910 and 1958 they found that in women born in the earlier years of study, there was little influence of genetic factors. However those born in later years of sample heritability was round 60%.
The rate for men in sample was relatively stable.
changing social attitudes of women smoking
Jason Boardmen et al studied siblings and twin pairs although strong genetic component in onset smoking, the rate of smoking varied across diff schools studied.
heritability was highest at schools where popular kids were smokers suggesting smoking is influenced by social factors rather than genetic predisposition