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Explanations for Nicotine Addiction: Brain Neurochemistry - Coggle Diagram
Explanations for Nicotine Addiction: Brain Neurochemistry
The desensitisation hypothesis:
Cigarette smoked
Nicotine released and enters the bloodstream
Nicotine activates nAChRs
Dopamine is released by the neuron
nAChRs shut down are desensitised
Dopamine is transmitted along the mesolimbic and mesocortical pathways
Dopamine arrives at the frontal cortex and nucleus accumbens
Rewarding effects occur
When smoking stops for some time the dopamine neurons resensitise
Evaluation:
McEvoy et al (1995)
- Support
Findings - smoking increased in schizophrenic patients given Haloperidol
Supports - biochemical approach as it suggests that the reason patients smoke more is because they crave the dopamine they are deprived from by the drug
Shows that + nicotine leads to + dopamine as they were looking to replace the reduced dopamine
However, patients are restricted sample therefore findings cannot be generalised to non-schizophrenics
Benwell et al (1990)
- Undermines
Findings - lower levels of 5-HT in the hippocampus of dependent smokers post mortem
Undermines - suggests that addiction is more complicated than simply the hypothesis
However, post mortems have low temporal resolution meaning it is difficult to establish the theory
Choi et al (2003)
- Undermines
Findings - 50% of people who experiment with cigarettes become dependent on nicotine and that adolescents who had friends who smoked, and who felt they were not doing as well at school were more tempted to start smoking
Undermines - suggests that other factors may be involved when it comes to addiction - too reductionist
However, demonstrated the importance of risk factors eg. peers
Shiffman et al (1995)
- Undermines
Findings - people known as 'Chippers' who smoke regularly do not get addicted
Undermines - suggests that the model cannot be applied to everyone due to individual differences ( lack of withdrawal symptoms suggests that its more holistic rather than reductionist)
Understanding of neurochemistry
- Support
Support - success of biological treatment supports the idea that addiction is biologically explained
However, deterministic, treatment may not work for everyone
The desensitisation hypothesis
- biological explanation of nicotine addiction
Conclusion:
Biological thus objective, but could be argued that the model for explaining addiction is too reductionist
Withdrawal and tolerance explained using the model:
Withdrawal - addicts would experience these effects due to the extra dopamine they are usually dependent on
Tolerance - Builds up when the addict is exposed to the rewarding effects more (More receptors needed, existing ones get chronically desensitised)