Biological Approach Flashcards
Initiation
Addicts inherit a genetic predisposition to developing an addiction.
Likely multiple genes are involved - focus on the A1 variant of the DRD2 gene - involved in the regulation of dopamine.
This gene may increase people’s sensitivity to dopamine.
Maintenance
The meso-limbic dopamine system which is concerned with memory reward and motivation. It is involved with the maintenance of addictive behaviour.
Cells in the meso-limbic dopamine system release small amounts of dopamine into the synapse. Addictive substances and behaviours increase dopamine levels in the synapse.
Addicts continue with their addictive behaviour because in order to experience the highs from the addiction, they need to maintain increasingly high levels of dopamine.
Falling levels of dopamine can lead to unpleasant withdraw symptoms. People who are more susceptible to addictions may have inherited a more sensitive meso-limbic dopamine system.
Relapse
Substances such as nicotine activate the dopamine reward pathway and the brain adapts to be in balance when the substance is present (neuroadaption).
When the substance is discontinued the adaption is no longer needed and is experienced as withdrawal symptoms which are unpleasant and are immediately relieved by using the substance.
Evaluation
Compared with other approaches the biological model does not explain initiation as well as the behavioural or cognitive model.
Has led to effective treatment such as the nicotine replacement therapy.
Absolves addicts of responsibility.
Best explanation - biopsychosocial model
Application to smoking - initiation
A meta analysis by Thorgerisson et al analysed data from 140,000 people and have discovered that there are DNA variants associated with whether people start smoking. It is convincing evidence because of the size of the study.
HOWEVER
The study shows a correlation between starting smoking and genetics not causation. It is likely that genetics only lead to a predisposition to become dependent - an environmental trigger
Application to smoking - maintenance
Schachter conducted a double blind study with adult smokers. Over a 4 week period ps alternated between smoking high and low nicotine cigarettes. They smoked low nicotine cigarettes for one week and high nicotine cigarettes the next. As the model predicts the subjects smoked more low than high nicotine cigarettes. This effect was especially strong for heavy smokers who smoked 25% more of the low than high nicotine cigarettes
Application to smoking - relapse
Lerman tested smokers when they had abstained from smoking for one night and found increased blood flow to the parts of the brain associated with memory, reward and learning - showing that these parts of the brain do become particularly active when a person is craving a cigarette
Application to gambling - initiation
Slutske looked at concordance rates of MZ and DZ twins in relation to gambling addiction. She studied nearly 5000 individuals and found that the concordance rate was twice as high for MZ twins as for DZ twins
Application to gambling - maintenance
Chase and Clark studied 24 regular gamblers. They completed a computerised gambling game based on slot machines whilst their mid brains were scanned using FMRI. Increased activity in the mesolimbic system resulted from wins but crucially also from near misses. In addition the higher the level of gambling severity the greater the response recorded.
Application to gambling - relapse
Stopping gambling results in the same kind of withdrawal symptoms associated with stopping drugs. Wray and Dickerson found 60% of pathological gamblers reported physical side effects during withdrawal and these were sometimes more severe than those reported by a comparison group during withdrawal from drugs
