Explanations for nicotine addiction: Brain neurochemistry Flashcards
What does Dani and Heinemann claim about nicotine addiction?
The focus of nicotine addiction comes in the form of two neurochemicals, Dopamine and Acetylcholine (Ach).
Acetylcholine has receptors all over the CNS, and is a key neurotransmitter in mental functioning.
One subtype of these receptors are called nicotinic acetylcholine receptors (nAChR). This is where the problem comes from, they can be activated by Acetylcholine or NICOTINE
What is Acetylcholine
Neurotransmitter that plays a role in memory, learning, attention and arousal and involuntary muscle movement
nAChRs and dopamine
- desensitised and downregulated
Subtype of Ach: nicotine acetylcholine receptor, activated by ACh or nicotine
When activated by nicotine…
- nAChRs are stimulated and transmit dopamine
- They then immediately shut down and temporarily cannot respond to neurotransmitters (nAChRs are desensitised, also downregulated because fewer active nAChRs are available)
Operant conditioning
- creating a pleasurable effect
nAChRs are concentrated in the ventral tegmental area (VTA) of the brain
When stimulated by nicotine, dopamine is transmitted along two pathways…
Mesolimbic pathway to the nucleus accumbens (NA), triggers dopamine to be released into the frontal cortex
Mesocortical pathway to release dopamine directly into the frontal cortex
Both are part of the dopamine reward system - when activated by nicotine creates pleasurable effects (mild euphoria, increased alertness, less anxiety)
Pleasurable response then becomes associated via operant conditioning with smoking
Withdrawal
- resensitised and upregulation
When you are not smoking (overnight), nicotine disappears from the body and nAChRs become functional again -> resensitised and upregulated (more available)
nAChRs are now overstimulated by Ach (no nicotine for them to bind with) and at their most sensitive - first cigarette of the day is the best (strongly activates DA reward system)
Dependence to nicotine
Unpleasant withdrawal symptoms are avoided by having another cigarette
- constant cycle of daytime downregulation and night time upregulation
- creating long term desensitisation of nAChRs i.e dependence
Tolerance to nicotine
Continuous exposure to nicotine cause permanent changes to brain neurochemistry (fewer active nAChRs)
Tolerance develops because a smoker has to smoke more to get the same effects
State two strengths of brain neurochemistry as an explanation for nicotine addiction
Indirect support
Neurochemistry leads to new treatments
EVALUATION: Indirect support
One strength of dopamine explanations is indirect support
Research by McEvoy et al. provides support to the idea that brain neurochemistry explains nicotine addiction.
They studied smoking habits in individuals with schizophrenia who are using haloperidol. This medication is classified as a dopamine antagonist since it lowers brain dopamine activity by blocking dopamine receptors.
It was found that there was an apparent increase in smoking among the drug users.
Therefore, patients sought nicotine in order to elevate their dopamine levels and feel euphoric, supporting the significance of dopamine as an explanation for nicotine addiction.
COUNTERPOINT TO McEvoy
Yet, despite dopamine’s essential role, other neurochemical systems—such as endogenous opioids (endorphins) and other neurotransmitters like GABA—as well as very complex pictures are also involved (Watkins et al).
Therefore, focusing solely on dopamine will not allow us to fully comprehend the neurochemistry of nicotine addiction.
EVALUATION: Neurochemistry leads to new treatments
One strength is that neurochemistry leads to new treatments
Among these is nicotine replacement treatment, which mimics the effects of nicotine from cigarette smoke by supplying a controlled dose of nicotine that binds with nAChRs. Dopamine release is one of these, soNRT fulfils cravings.
By progressively lowering their nicotine dosage, users can lessen withdrawal symptoms. Therefore, a better knowledge of neurochemistry has resulted in a successful nicotine addiction treatment.
ALTERNATIVE EXPLANATION: Learning theory
Social learning theory offers another explanation for nicotine addiction.
This would imply an individual learns to smokethrough witnessing a role model, like a parent or friend, smoke.
The person may mimic their smoking behaviour because they relate to them and aspire to be like them.
Another factor that may come into play is vicarious reinforcement. If someone sees a peer or other role model being popular for smoking, for example, they may decide to start smoking themselves in order to receive the same benefit.
This is in contrast to the explanation provided by brain neurochemistry, which states that high dopamine levels trigger activation of the brain’s reward pathway
Thus, there are other explanations for addiction outside brain neurochemistry that need to be taken into account.
EVALUATION: Determinism
The neurochemical explanation is biologically determinist. Chemical events in the brain are beyond out control, including withdrawal. So nicotine addiction is inevitable in someone who starts smoking
May not be inevitable - some smoke without becoming dependent (Schiffman) and some find it easier because of personality factors (Gilbert)
Suggesting it is inevitable for many people because of neurochemistry of addiction/personality but some people override this
EVALUATION (limitation): Doesn’t explain withdrawal
One limitation is the neurochemical explanation doesn’t explain withdrawal
According to the explanation, the level of nicotine in the blood is the primary factor influencing withdrawal symptoms.
However, there is little correlation between these variables. Gilbert argues that personality and environment have a greater influence on withdrawal symptoms; for example, withdrawal symptoms are more severe in neurotic individuals than in emotionally secure individuals.
Therefore, withdrawal symptoms might be explained in many different waysapart compared to amounts of nicotine.
