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NICOTINE ADDICTION: BRAIN CHEMISTRY - Coggle Diagram
NICOTINE ADDICTION: BRAIN CHEMISTRY
Nicotine
it binds to the nicotinic acetylcholine receptor
nicotine imitates the action of a natural neurotransmitter called acetylcholine
dopamine reward pathway
trigger the release of the neurotransmitter dopamine the nucleus accumbens - leading to feeling of pleasure
boosts activity in the prefrontal cortex
nicotine binds to the nicotinic acetylcholine receptor sites on the neurons of the VTA
pleasure encourages the individual to repeat the smoking behaviour
downregulation and upregulation
smokers develop a tolerance to nicotine and experience reduced pleasure from it over time
they become desensitised to the effects of nicotine, they need to smoke more to achieve the same desired effect
chronic smokers maintain a high enough concentration of nicotine to deactivate the receptors and slow down their recovery, cannot be triggered by acetylcholine - downregulation
nicotine regulation model
individuals smoke to avoid withdrawal symptoms
due to nicotine levels in the blood dropping
causes a decrease in dopamine levels
become sensitive to the effects of acetylcholine again, resulting in feelings of anxiety, agitation and restlessness
research support - watkins et al. 2000
found that dopamine release was reduced following chronic exposure to nicotine
explains how a tolerance to nicotine develops over a time as the level of reward felt decreases with prolonged exposure
research into neurobiology of nicotine addiction
partial explanation
there are many other neurochemical mechanisms involved and that there is a vastly complex interaction of neurochemical systems
eg GABA and serotonin
dopamine is only part of the neural action, there are several complex explanations
however dopamine is arguably central to the neurochemistry of nicotine addiction
DRD2 gene
comings et al found that nicotine addicts show a greater prevalence of the A1 variant of the DRD2 gene
48% in smokers, compared to 25% amongst non smokers
dopamine could further support the idea that there is a genetic link to smoking addiction
related to fewer dopamine receptor sites and lower levels of dopamine in the brain
therefore lead them to feel the rewarding effects of nicotine to a greater extent
reductionist
only explains nicotine addiction on a biological level, psychological and social factors also play an important role in nicotine addiction
cannot offer a complete explanation for nicotine addiction.
neurochemical explanation is considered to be reductionist