Nicotine Addiction- Brain chemistry and Dopamine

Question 1

What is one explanation for the initiation of smoking?

Answer 1

• Some people inherit a genetic vulnerability to start smoking and therefore develop an addiction
• 1 candidate gene for smoking is the A1DRD2 variation which codes for defective and insufficient dopamine receptors within the brain
• Means that some individuals cannot naturally produce pleasure so may engage in smoking to raise dopamine to optimal levels

Question 2

What is the role of dopamine in smoking?

Answer 2

1. Nicotine stimulates specific acetycholine receptors which increase alertness, memory function and learning
2. This causes a rise in dopamine activity in the ventral tegmental area (critical area in the brains reward circuity which is highly populated with nicotine acetylcholine receptors), giving nicotine a rewarding sensation
3. The ventral tegmental area activity caused by nicotine is then projected to the nucleus accumbens, a producer of dopamine boated deep in the mesolimbic dopamine pathway
4. The nucleus accumbens is a primary reward centre in the brain and with increased activity dopamine rises, causing users to evaluate smoking as very pleasurable, compelling further use
5. At the same time, the nucleus accumbens is encouraged to release more dopamine as nicotine also stimulates endorphins that reduce GABA activity. A decrease in GABA correlates with further rises in dopamine meaning more and more dopamine forces smokers to engage with further use

Question 3

What is the process of smoking relapse and down/up regulation?

Answer 3

1. Nicotine triggers the firing of dopamine in the mesolimbic dopamine pathway, acting like a reward for the smoker
2. As a reward, the smoker wants this again, but tolerance develops
3. With long term use, the nicotine regulation model by Schachter suggests that the smokers’ reward system becomes less sensitive as specific acetylcholine receptors become unavailable and inactive
4. This can create anxiety, lethargy and sadness
5. To avoid this, smokers continue to smoke more to maintain a certain level of nicotine in their bodies to avoid these unpleasant side effects
6. Hence, with the down regulation in the mesolimbic pathway, an increased amount of nicotine is needed to achieve the same initial kick as the rewarding receptors have been ground down

Question 4

If the point is:

A strength of the biochemical explanation for nicotine addiction is that there is some support that illustrates its involvement.

What is the evidence, explanation and link?

Answer 4

Evidence- Paterson et al found support for the role of nicotine and dopamine through research with the epilepsy drug Gamma vinyl GABA.

Explanation- This drug reduces the surge of dopamine in the nucleus accumbens that occurs after nicotine. This effectively reduces the addictive properties of nicotine without major side effects.

Link- This suggests that nicotine certainly causes a rise in dopamine and this is partly why many see it as so rewarding and becoming addicted, providing credibility to the theory.

Question 5

If the point is:

A strength of the biochemical explanation for nicotine addiction is that it has led to some useful practical applications.

What is the evidence and link?

Answer 5

Evidence- Nicotine replacement theory works by delivering therapeutic doses of nicotine in the early stages of stopping smoking. This release of nicotine is absorbed much more slowly and steadily than in tobacco. Davison found that the use of inhalers has been shown to keep 28% of treatment groups off of cigarettes for 12 months.

Link- This implies that the brain chemistry account of smoking addiction has the potential to help the 19% of smokers in the UK ditch the habit.

Question 6

If the point is:

A weakness of the biochemical explanation for nicotine addiction is that it only appears to offer an account of the nature side of addiction and neglects to consider the role of nurture.

What is the evidence and link?

Answer 6

Evidence- Perhaps the rewarding qualities of nicotine are also gained through the environment. For example, the peer acceptance and approval that have been shown to be positively reinforcing. Research has shown that nicotine activates dopamine, but studies have also shown peer approval activates dopamine too.

Link- This could imply that the explanation could be more comprehensive if it takes into account nurturing influences of nicotine addiction.

Question 7

If the point is:

A strength of the biochemical explanation for nicotine addiction is that it’s praised for its scientific methodology.

What is the evidence and link?

Answer 7

Evidence- The dopamine account uses both empirical and falsifiable methods to help identify the biochemical action of nicotine. For instance, dopamine and NAcR can be objectively measured through cerebrospinal fluid, sophisticated PET scans and carefully examining urine for waste products.

Link- This means the dopamine account of nicotine addiction is likely to be trustworthy and reliable.

Question 8

What are the evaluation points for the biochemical explanation of nicotine addiction?

Answer 8

+ There is some support that illustrates the involvement of dopamine with smoking addiction

+ Led to some useful practical applications

– Only appears to offer an account of the nature side of nicotine addiction and neglects to consider the role of nurture

+ Praised for its scientific methodology