Addiction: Biological explanations for nicotine addiction Flashcards
What is the neurotransmitter for nicotine?
ACh
ACh plays a key role in all nervous system activity, which means there are ACh receptors on the surfaces of many ______ in the _________.
Neurons
Central nervous system
nACHR receptors are activated by ____/______.
ACh/nicotine
When nAChRs are activated by nicotine molecules, the neuron transmits _______.
Dopamine
nAChRs are activated by nicotine molecules and transmits dopamine. This is immediately followed by shutdown- where they cannot respond to _______.
Neurotransmitters.
When nAChRs cannot respond to neurotransmitters, they are said to be ________.
Desensitised.
What is the result of nAChRs becoming desensitised?
- Leads to a downregulation
- A reduction in the number of active neurons because fewer of them are available.
Where are nAChRs found?
Ventral Tegmental Area (in the brain)
What happens when nAChRs are stimulated by nicotine?
- Neurons transmit dopamine along the mesolimbic pathway to the nucleus accumbens (NA).
- This triggers the release of more dopamine from the NA to the frontal cortex.
- Dopamine is also transmitted along the mesocortical pathway to the frontal cortex
Give 3 impacts of the brain’s dopamine reward system being activated (via nicotine):
- Mild euphoria
- Increased alertness
- Reduction of anxiety
What are the two pathways that are a part of the brain’s dopamine reward system?
- Mesolimbic
- Mesocortical
Explain how withdrawl occurs:
- A person does not use nicotine for a prolonged period of time- no nicotine in their system/body
- nAChRs become functional again, so dopamine neurons resensitise and become more available.
- nAChRs become overstimulated by ACh (because there is no nicotine to bind to them), which increases their sensitivity.
Why do smokers often say that their first cigarette of the day is the best?
- Withdrawl starts to occur
- nAChRs become functional, sop dopamine receptors resensitise and become more available
- nAChRs become overstimulated by ACh, which increases their sensitivity
- The first cigarette of the day reactivates the dopamine reward system, alongside the increased nAChR sensitivity.
Explain dependence and tolerance in terms of nicotine addiction:
- The smoker avoids unpleasant physiological and psychological withdrawl states by having another cigarette.
- This creates a constant cycle of daytime downregulation and nighttime upregulation, creating long-term desensitisation of nAChRs.
- Continuous exposure to nAChRs causes permanent changes to brain neurochemistry- a decrease in the number of active receptors.
- A tolerance develops as a smoker has to smoke more to get the same effects.
Name the 4 evaluation points for nicotine addiction via brain neurochemistry:
- Research support (S)
- Real world application (S)
- Withdrawl symptoms (L)
- Determinism (L)
Explain research support (S) as an evaluation point for nicotine addiction via brain neurochemistry:
- Support from human research
- McEvoy studied schizophrenics who were taking a dopamine antagonist drug (reduces dopamine transmission).
- The schizophrenics showed a significant increase in smoking.
- This was because they used smoking as a form of self-medication, they used nicotine as a way to make up for the dopamine loss.
- Supports the view that dopamine has a key role in the neurochemistry of nicotine addiction.
Explain real world application (S) as an evaluation point for nicotine addiction via brain neurochemistry:
- Neurochemistry leads to new treatments e.g. nicotine replacement therapy (NRT)
- NRTs deliver a controlled dose of nicotine
- This nicotine binds to nAChRs and mimics the effects of nicotine from cigarettes, inducing dopamine release
- Allows for cravings to be satisifed in a way where dosage is cleaner and can be reduced
Explain determinism (L) as an evaluation point for nicotine addiction via brain neurochemistry:
- The neurochemical explanation does not fully explain withdrawl.
- The theory states that withdrawl symptoms mainly depend upon the amount of nicotine in the body (e.g. levels of nicotine within the blood)
- Gilbert states that these factors are not strongly correlated. He argues that withdrawl depends more on environment and personality
- E.g. people with neuroticism generally experience worse withdrawl symptoms than people who are emotionally stable
Explain determinism (L) as an evaluation point for nicotine addiction via brain neurochemistry:
- The neurochemical explanation is biologically deterministic
- Suggests that we become addicted to nicotine because of chemical events involving the dopamine reward system that is beyond our control, including withdrawl.
- So nicotine addiction is inevitable for someone who starts smoking.
- However it may not be inevitable for everyone as some people start to smoke but do not become addicted, e.g. due to their personality.
