A- Biological explanations Flashcards
what is the first biological explanation of addiction
dopamine
what do addictive behaviours and substances trigger
a release of dopamine in the mesolimbic pathway
what is the mesolimbic pathway responsible for
the reward sensation, pleasurable activities such as eating but also drug taking trigger the release of dopamine which basically tells the brain to do it again
explain how crack cocaine has an affect on the brain
causes a massive and rapid activation of dopamine receptors in the mesolimbic pathway, creating a lasting memory that link that drug to a pleasurable reward
who proposed incentive sensitisation theory and what is it
robinson and berridge
repeated exposure to drugs of abuse leads to increasing sensitivity of the brain which can persist even without continued exposure of the drug
explain maintenance
continued exposure to to the drug eventually results in a reduction of the activity of these positive reward circuits in the brain (downregulation) as the dopamine receptors become less sensitive to the effects
what happens as a result of downregulation
a chronic stress situation for the addict (withdrawal symptoms, sadness and anxiety) this than causes the drug craving, may no longer enjoy the drug taking but do it to avoid the withdrawal symptoms. the addict also becomes tolerant
explain relapse (dopamine explanation)
the desire for drugs becomes the most important desire, despite the drug no longer providing much pleasure the brain is still receiving signals of reward that force the addict to relapse and take the drug again
why is permanent recovery made more difficult
due to the drug-induced changes in the frontal cortex that creates a lasting memory of the drug
\explain the frontal cortex’s link to addiction
area of the brain liked to cognitive functioning (decision making and memory) addicts have learned to expect a rewarding experience from the drug, when the individual tries to withhold from the drug the constant release of dopamine predicts a reward, this happens even if the addict knows the rewards isn’t coming because their self control has weakened. the frontal cortex has become less effective at making decisions and judging the consequences of their actions. this heightens the risk of relapse
one strength of the dopamine explanation
practical applications, positive effective treatment for addictive behaviours
evidence to support practical applications of addiction
Botswick and Bucci
treated a young adult male patient who was addicted to sex. he had a strong appetite for pornography, engaged in phone sex in his teens and in his 20s would spend hours searching for ‘sexual gratifying activity’ he was treated with nalextrone which effectively blocked the release of dopamine associated with the sexual activities. blocking the reward stopped the power of his addiction, his psychosexual functioning dramatically improved
what does Botswick and Bucci’s research suggest
that the drug therapies created as a result of this explanation can go some way to improving the lives of real people
a second strength of the dopamine explanation
theres supportive evidence which can account for individual differences in addiction
evidence to support individual differences in addiction
Volkow et al gave Ritalin (which gently lifts dopamine levels) to a group of volunteers. some of them loved the feeling of the drug and others hated it. they then produced scans of their brains and found that those who liked the rush from the drug had fewer dopamine receptors compared to those that hated it,
what did Volkow et al conclude from his research
that some people are particularly vulnerable to the rush given by dopamine enhancing drugs, but others cannot take further stimulation
what does Volkows research suggest/explain
this could explain why some people after experimenting with drugs, might go on to develop an addiction whilst others may not (even with the same initial experience) this seems to be the case of real world human behaviour so supports this biological explanation
a weakness to the dopamine explanation
not all addictions seem to increase dopamine levels, although there is significant evidence to demonstrate the increased levels of dopamine following the consumption of some drugs, this is not the case for all addictive behaviours and substances which cannot be ignored
researchers that don’t agree with this explanation due to not all addictions showing increased dopamine levels
Stokes et al. found no significant increase in levels of dopamine in volunteers taking cannabis
Yoder et al. found no consistent increase in dopamine across the participants in their study who were given alcohol
what does Yoder and Stokes research suggest
we must proceed with caution before suggesting all addictions can be put down to the action of dopamine on the brain when this is not the case
another weakness of the dopamine explanation
explaining addiction as being down to dopamine alone is too simplistic and fails to recognise that dopamine has a range of other functions besides providing a reward sensation
research to support the dopamine explanation being too simplistic
(2 pieces)
Bell refers to dopamine as the ‘Kim Kardashian of neurotransmitters’ suggesting it has become fashionable to blame dopamine for causing a range of problems, whereas the actual brain systems that must be involved will be many and varied
studies have also suggested that dopamine levels also increase in the presence of unpleasent stimuli, Lierzon et al showed increased activation in the mesolimbic pathway of war veterans suffering from PTSD when reminded of battle through combat sounds.
what does Bell and lierzons research suggest
these findings are in direct opposition to what we would predict about dopamine if we are to believe that it is the cause of addictive behaviour therefore weakening the explanation.
what is the second biological explanation of addiction
genes
genes and addiction
if addictions are caused by genes then we should expect those who are closely related to share tendancies and become addicts
what did Goldman et al find
concluded that addictions were moderate to highly heritable, the heritability for addictions ranges from +0.39 for hallucinogens to +0.72 for cocaine
as genetic similarity increases, so does the likelihood of being addicted to these drugs
explain the D2 dopamine receptor gene
research began to link the D2 dopamine receptor gene to sever alcoholism.
what did Noble et al find
Noble et al found that the A1 variant of the gene was present in more than two thirds of deceased alcoholics, only one fifth of deceased non-alcoholics had this gene
what did Blum et al find
found an increased prevelance of the A1 variant among children born to alcoholics possibly reflecting the increased intra-family risk
people with the A1 variant..
appeared to have significantly lower dopamine receptors in the pleasure centres of the brain, Noble et al named this gene ‘the reward gene’
people who inherit this gene are more likely to develop addictions to drugs that increase dopamine levels, the result is that their addiction is maintained because it’s is only with the addictve activity that they feel good
what addictions has the A1 variant been linked to
cocaine, heroin and nicotine
explain how the diathesis stress model is linked to the second biological explanation for addiction
might consider how our genes and environment might interact to produce particular outcomes, this is interactionist. suggesting an addiction will only develop when a genetic predisposition to a particular condition is combined with the right environmental factors
what did Kaufman et el find
the seretonin transported gene has been linked to the development of alcoholism, but the presence of the gene is not enough to investigate addiction. but if someone with this gene were also to have experienced environmental stressors like being maltreated as a child, this would significantly increase the likelihood of the onset of an addiction.
strength of the gene explanation for addiction
supportive evidence from its proposals from twin studies
evidence for the strength of biological explanation 2
Kendler and Prescott interviewed nearly 2,00 twins and found that although environmental and social factor were important in influence whether a person would begin cocaine use, whether a person became addicted was more down to genetic factors. founf the concordance rate for cocaine initiation in MZ twins was 54% and for DZ twins it was 42%.
when looking at concordance rate for dependence on cocaine, there was a substantial difference between MZ and DZ twins. (35% and 0%)
what does Kendler and prescot’s findings suggest
there is a role for genetics when it comes to addictive behaviours as opposed to the decision.
what is meant by the term concordance rate
describe the rate of probability that two people with shared genes will develop the same organic disease
weakness of biological explanation 2: genes
there are problems linked with one of the most prominent proposals
research to back the weakness of biological explanation 2
Comings et al. found that the A1 gene variant occureed in people with several disorders, (including autism and tourettes) at least as often as it appeared in alcoholics.
the A1 variant of the dopamine receptor gene was present in 45% of the tourettes patients compared with 25% of comtrols
what does comings research suggest
it creates a problem for the idea that the dopamine receptor gene is a ‘reward gene’ since people with autism and tourettes are not thought to be particularly pleasure seeking. so this explanation is limited.
PB point for Botswick and Bucci research
first biological explanation
they only looked at the use of nalextrone to treat an addiction to sex, therefore we cannot generalise the findings to all addictions and also to all individuals as the sample was only on individual
