Neurochemistry and Nicotine Addiction | AQA A-Level Psychology Revision
- Revision Notes
- Aug 7
- 31 min read
Updated: Aug 14
For 7182 specification, first teach in September 2025
AQA A-Level Psychology | Free Revision Notes
Estimated study time: 65 to 80 minutes
Neurochemistry and nicotine addiction A-Level Psychology revision examines how nicotine alters communication within the brain. Nicotine binds to nicotinic acetylcholine receptors and stimulates the brain’s reward pathway, increasing dopamine activity and producing pleasurable effects. Repeated stimulation can contribute to tolerance, craving, withdrawal and continued smoking.
You will learn the sequence linking nicotine with the ventral tegmental area and nucleus accumbens, while evaluating whether dopamine alone provides a complete explanation. The AQA specification requires brain neurochemistry, including the role of dopamine, as an explanation for nicotine addiction.
Learning Objectives 🎯
By the end of this revision page, you should be able to:
Define brain neurochemistry.
Explain how nicotine affects nicotinic acetylcholine receptors.
Describe the mesolimbic reward pathway.
Explain the roles of the ventral tegmental area, nucleus accumbens and dopamine.
Explain how neurochemical adaptation contributes to tolerance, withdrawal and craving.
Apply the neurochemical explanation to unfamiliar examples of nicotine use.
Evaluate the explanation using evidence, methodological concerns, reductionism and alternative explanations.
Judge whether the explanation is more successful in accounting for the initiation or maintenance of smoking.
Revision Notes 📚
Neurochemistry and Nicotine Addiction A-Level Psychology Revision Focus
Brain neurochemistry concerns the chemical processes through which brain cells communicate and regulate behaviour.
Relevant chemical messengers include:
Neurotransmitters.
Naturally occurring opioids.
Chemicals that activate or inhibit receptors.
The neurochemical explanation proposes that nicotine addiction develops and is maintained because nicotine alters chemical transmission in brain systems associated with:
Reward.
Pleasure.
Motivation.
Learning.
Anxiety.
Craving.
Withdrawal.
The central AQA sequence is:
Nicotine binds to nicotinic receptors → dopamine is released in the brain’s reward pathway → pleasurable effects reinforce smoking → repeated exposure produces adaptation, tolerance and withdrawal → craving motivates further smoking
AQA’s November 2020 mark scheme identifies nicotinic receptors, the ventral tegmental area, the nucleus accumbens, dopamine, tolerance and withdrawal as the central elements of this explanation.
Neurons and Neurotransmitters
What Is a Neuron?
A neuron is a specialised cell that transmits information within the nervous system.
Neurons communicate through:
Electrical activity within the neuron.
Chemical transmission between neurons.
The small gap between neurons is called the synapse.
What Is a Neurotransmitter?
A neurotransmitter is a chemical messenger released by one neuron that affects another neuron.
The basic sequence is:
An electrical impulse reaches the end of a neuron.
Neurotransmitter molecules are released.
The molecules cross the synaptic gap.
They bind to matching receptors.
The receiving neuron is excited or inhibited.
The neurotransmitter is then removed, broken down or taken back into the original neuron.
Receptors
A receptor is a specialised structure to which a particular neurotransmitter or drug can bind.
The relationship is often compared with a lock and key:
The receptor is the lock.
The chemical molecule is the key.
Nicotine can bind to receptors that normally respond to the neurotransmitter acetylcholine.
These are called nicotinic acetylcholine receptors.
Nicotine Is Not a Neurotransmitter
Nicotine is a chemical found in tobacco products.
It is not naturally released by the brain as a neurotransmitter.
However, its molecular properties allow it to activate some receptors that normally respond to acetylcholine.
This alters neuronal activity and neurotransmitter release.
Acetylcholine
The Normal Role of Acetylcholine
Acetylcholine, often abbreviated to ACh, is a neurotransmitter involved in several processes, including:
Arousal.
Attention.
Learning.
Memory.
Muscle activity.
There are different types of acetylcholine receptor.
The receptors relevant to nicotine addiction are nicotinic acetylcholine receptors, often abbreviated to nAChRs.
Nicotinic Acetylcholine Receptors
These receptors are naturally activated by acetylcholine.
Nicotine can also bind to them.
Nicotine therefore acts as an agonist.
An agonist is a chemical that:
Binds to a receptor.
Activates the receptor.
Produces or increases a biological response.
Nicotine does not simply create dopamine directly. It begins a sequence of neuronal activity that results in greater dopamine release.
The Brain Reward System
What Is the Reward System?
The brain’s reward system is a network of structures involved in:
Pleasure.
Motivation.
Reinforcement.
Learning which behaviours should be repeated.
Natural rewards can activate this system.
Examples include:
Eating.
Social interaction.
Achievement.
Enjoyable activities.
Nicotine can stimulate the same general reward pathway more directly.
The Mesolimbic Pathway
The pathway most commonly associated with nicotine addiction is the mesolimbic dopamine pathway.
Important parts include:
The ventral tegmental area.
Dopamine-producing neurons.
The nucleus accumbens.
Other structures within the limbic system.
AQA describes this as the common reward pathway or reward centre of the brain.
A Simplified Pathway
The central sequence is:
Nicotine enters the bloodstream.
Nicotine reaches the brain.
It binds to nicotinic acetylcholine receptors.
Receptors on or connected with neurons in the ventral tegmental area are activated.
Dopamine-producing neurons become more active.
Dopamine is released in the nucleus accumbens.
The smoker experiences rewarding effects.
Smoking becomes more likely to be repeated.
A high-quality answer should explain the sequence rather than merely state:
Nicotine releases dopamine.
The Ventral Tegmental Area
What Is the Ventral Tegmental Area?
The ventral tegmental area, often abbreviated to VTA, is a region containing dopamine-producing neurons.
These neurons project to other parts of the brain, including the nucleus accumbens.
Nicotine binds to nicotinic receptors within this system and increases the activity of dopamine neurons.
The VTA therefore acts as an important starting point within the reward pathway.
Applying the VTA
A student might write:
When nicotine reaches the brain, it binds with nicotinic acetylcholine receptors in the ventral tegmental area. This increases activity in dopamine-producing neurons, which project to the nucleus accumbens.
This provides a clearer biological mechanism than:
Smoking affects the pleasure part of the brain.
The Nucleus Accumbens
What Is the Nucleus Accumbens?
The nucleus accumbens is a structure within the reward system that receives dopamine projections from the VTA.
Increased dopamine activity within the nucleus accumbens is associated with:
Reward.
Pleasure.
Motivation.
Reinforcement of behaviour.
When smoking increases dopamine transmission in this area, the smoker is more likely to repeat the behaviour.
The Nucleus Accumbens and Reinforcement
The nucleus accumbens helps the brain learn that particular actions predict rewarding outcomes.
The process may be:
Smoking → dopamine activity increases → reward is experienced → the brain learns that smoking is worth repeating
This creates a biological basis for reinforcement.
Dopamine
What Is Dopamine?
Dopamine is a neurotransmitter involved in:
Reward.
Motivation.
Reinforcement.
Learning.
Movement.
In nicotine addiction, the key role of dopamine is within the mesolimbic reward pathway.
Nicotine increases dopamine action, stimulating the reward pathway and producing feelings of euphoria. This was the precise correct relationship tested in AQA’s June 2025 examination.
Dopamine and Pleasure
When nicotine increases dopamine transmission, the smoker may experience:
Pleasure.
Satisfaction.
Mild euphoria.
Reduced tension.
Reduced anxiety.
Increased motivation to smoke again.
The exact subjective effect varies between individuals.
The important psychological consequence is that smoking becomes rewarding.
Positive Reinforcement
Positive reinforcement occurs when behaviour becomes more likely because it produces a rewarding consequence.
In nicotine addiction:
The person smokes.
Nicotine activates nicotinic receptors.
Dopamine activity increases.
A rewarding effect is experienced.
Smoking becomes more likely to occur again.
The pleasurable consequence positively reinforces smoking.
This relationship is developed further in operant conditioning and smoking behaviour [Lesson 5: Learning theory and nicotine addiction].
Dopamine Does Not Simply Equal Pleasure
It is too simplistic to say:
Dopamine is the pleasure chemical.
Dopamine is involved in:
Motivation.
Learning about rewards.
Wanting or seeking rewards.
Reinforcing behaviour.
The person may eventually experience a strong desire to smoke even where the pleasurable effect has become weaker.
This helps explain why:
Wanting and liking are not always identical.
Smoking may continue after enjoyment has decreased.
Cues can trigger strong motivation.
Reward Prediction
With repeated nicotine use, the brain may learn that particular actions or situations predict nicotine reward.
Examples include:
Opening a cigarette packet.
Holding a lighter.
Finishing a meal.
Taking a work break.
Meeting friends who smoke.
Dopamine activity is therefore relevant not only to immediate reward but also to learning which cues predict reward.
The detailed conditioning process is examined in learned associations and cue reactivity [Lesson 5: Learning theory and nicotine addiction].
Nicotine and Positive Reinforcement
Early Smoking
During early smoking, nicotine may produce rewarding effects that encourage repetition.
The process may be:
A person tries smoking.
Nicotine stimulates the reward pathway.
The person experiences pleasure or relief.
Smoking is positively reinforced.
The person becomes more likely to smoke again.
However, neurochemistry may not fully explain why the first cigarette was tried.
Initial exposure may result from:
Family modelling.
Peer pressure.
Curiosity.
Availability.
Sensation seeking.
Social approval.
These are covered in personality and social risk factors [Lesson 3: Personality and social influences].
Continued Smoking
As smoking continues, the motivation may shift.
The person may begin by smoking to obtain pleasure but later smoke to:
Avoid withdrawal.
Remove craving.
Feel normal.
Improve concentration.
Reduce irritability.
Nicotine addiction therefore involves both:
Obtaining rewarding effects.
Avoiding unpleasant effects of abstinence.
Neuroadaptation
What Is Neuroadaptation?
Neuroadaptation refers to changes in brain functioning following repeated exposure to a substance.
The nervous system attempts to adjust to the repeated presence of nicotine.
These adaptations may involve:
Receptor sensitivity.
Receptor availability.
Dopamine activity.
Other neurotransmitter systems.
The level of stimulation needed for a rewarding effect.
Neuroadaptation contributes to:
Tolerance.
Physical dependence.
Withdrawal.
Craving.
The Brain Attempts to Maintain Balance
The body normally attempts to maintain a stable internal state.
This is called homeostasis.
Repeated nicotine exposure disrupts ordinary neurochemical activity.
The brain compensates for this repeated stimulation.
When nicotine is then absent, the compensatory changes remain temporarily, producing an unbalanced state and withdrawal symptoms.
Receptor Desensitisation
What Is Desensitisation?
With repeated nicotine exposure, some nicotinic receptors become less responsive to continued stimulation.
This is called desensitisation.
The original nicotine dose may therefore produce a weaker effect.
The person may smoke:
More frequently.
More cigarettes.
Stronger products.
Soon after nicotine levels fall.
Desensitisation is one mechanism that may contribute to tolerance.
Increased Receptor Availability
Repeated nicotine exposure may also lead the brain to alter the number or availability of nicotinic receptors.
AQA’s nicotine-regulation account emphasises that abstinence increases receptor sensitivity, contributing to withdrawal and renewed motivation to smoke.
The detailed biological changes are complex, but the A-Level sequence is:
Repeated nicotine exposure changes receptor functioning → nicotine becomes less effective → more nicotine is needed → abstinence creates discomfort and craving
Tolerance
What Is Tolerance?
Tolerance occurs when repeated exposure reduces the effect of a substance, so a larger amount is needed to produce the previous effect.
In nicotine addiction:
The original amount of nicotine becomes less effective.
The smoker increases nicotine intake.
More nicotine is required to achieve comparable reward or relief.
AQA explicitly links repeated activation of nicotinic receptors with needing more nicotine to produce the same effect.
A Neurochemical Explanation of Tolerance
The process may be:
Nicotine repeatedly activates nicotinic receptors.
The brain adapts to the repeated stimulation.
Receptor and neurotransmitter responses change.
The original dose produces less dopamine-related reward.
The smoker increases nicotine consumption.
The increased dose temporarily restores the desired effect.
Applying Tolerance
Eleni used to feel satisfied after smoking one cigarette. She now needs to smoke three cigarettes within the same period to experience a similar effect.
This indicates tolerance because:
The previous amount is less effective.
A larger dose is needed for the same result.
Repeated nicotine exposure may have produced neurochemical adaptation.
Tolerance should not be confused with simply wanting to smoke more.
The same-effect relationship must be clear.
Physical Dependence
Neurochemistry and Physical Dependence
Physical dependence occurs when the body has adapted to the repeated presence of nicotine and begins to function as though nicotine is required.
The smoker may need nicotine to:
Avoid discomfort.
Maintain concentration.
Regulate mood.
Feel normal.
The body’s expected state now includes nicotine-related stimulation.
This connects with physical dependence, psychological dependence, tolerance and withdrawal syndrome [Lesson 1: Describing addiction].
Dependence Changes the Motivation to Smoke
Before dependence:
The person may smoke to obtain a pleasurable effect.
After dependence:
The person may smoke because the absence of nicotine produces discomfort.
This shift is important.
The person may continue smoking even when:
Pleasure has decreased.
They understand the health risks.
They want to stop.
Smoking is expensive.
Other people disapprove.
Withdrawal
What Is Withdrawal?
Withdrawal syndrome is a collection of physical and psychological symptoms appearing when nicotine use is reduced or stopped.
Possible nicotine-withdrawal symptoms include:
Irritability.
Restlessness.
Craving.
Anxiety.
Low mood.
Concentration difficulties.
Sleep disturbance.
Increased appetite.
The exact pattern varies between smokers.
The Neurochemical Basis of Withdrawal
When nicotine levels fall:
Nicotinic receptors are no longer being stimulated at the accustomed level.
Dopamine-related reward activity decreases.
The brain’s adapted state is disrupted.
The person experiences craving or discomfort.
Motivation to restore nicotine levels increases.
AQA’s nicotine-regulation model highlights abstinence, increased receptor sensitivity, withdrawal and the resulting motivation to smoke.
Overnight Abstinence
During sleep, the smoker usually goes several hours without nicotine.
By morning:
Nicotine levels have fallen.
Receptors are more responsive after the period without stimulation.
Withdrawal or craving may be present.
Smoking quickly restores receptor activation and dopamine activity.
This helps explain why some dependent smokers report a particularly strong desire for a cigarette soon after waking.
Withdrawal and Dopamine
During abstinence, the reward system is no longer being stimulated as expected.
Ordinary activities may temporarily feel less rewarding.
The person may report:
Low mood.
Lack of pleasure.
Reduced motivation.
Difficulty concentrating.
Smoking raises nicotine and dopamine activity again, reducing the unpleasant state.
Negative Reinforcement
Smoking to Remove Withdrawal
Negative reinforcement occurs when behaviour increases because it removes an unpleasant condition.
In nicotine addiction:
Nicotine levels fall.
Withdrawal symptoms appear.
The person smokes.
Nicotine activates the reward system.
Withdrawal symptoms decrease.
Relief negatively reinforces smoking.
The person learns:
Smoking removes discomfort.
This is different from positive reinforcement.
Positive reinforcement | Negative reinforcement |
Smoking adds a rewarding effect | Smoking removes an unpleasant effect |
Pleasure or euphoria follows nicotine | Withdrawal or craving is reduced |
Behaviour increases | Behaviour increases |
Important during rewarding use | Important once dependence develops |
Both processes can maintain nicotine addiction.
Craving
What Is Craving?
A craving is a powerful urge or desire to use nicotine.
Craving may have:
Biological components.
Psychological components.
Learned components.
The biological explanation emphasises:
Reduced nicotine stimulation.
Altered dopamine activity.
Receptor sensitivity.
Withdrawal.
Learning theory emphasises:
Environmental cues.
Conditioned associations.
Expectations.
Previous reinforcement.
Craving is therefore best understood as involving interacting processes.
Craving and Relapse
Relapse means returning to smoking after attempting to stop.
Cravings may produce relapse because:
They are unpleasant.
The smoker expects rapid relief from nicotine.
Nicotine has repeatedly removed withdrawal.
The reward system motivates nicotine seeking.
Environmental cues activate learned expectations.
A biological account helps explain why the craving occurs during abstinence.
A learning account helps explain why a particular situation triggers it.
The Nicotine Regulation Model
What Is the Nicotine Regulation Model?
The nicotine regulation model proposes that dependent smokers regulate their nicotine intake to maintain a preferred level and avoid withdrawal.
The smoker may adjust:
Number of cigarettes.
Time between cigarettes.
Depth of inhalation.
Amount smoked from each cigarette.
The process can be represented as:
The smoker consumes nicotine.
Nicotine levels rise.
Reward and relief occur.
Nicotine is gradually metabolised.
Nicotine levels fall.
Withdrawal and craving begin.
The smoker consumes more nicotine.
Nicotine levels are restored.
Self-Regulation Does Not Mean Free Control
The term regulation does not mean that the smoker is freely controlling the addiction.
Their behaviour is influenced by:
Neurochemical dependence.
Withdrawal.
Craving.
Learned routines.
Availability.
Social conditions.
The smoker is regulating nicotine partly to prevent an unpleasant neurochemical state.
Applying the Regulation Model
Theo smokes soon after waking, again during his journey to work and repeatedly throughout the day. If he cannot smoke for several hours, he becomes irritable and struggles to concentrate.
Application:
Nicotine levels fall during periods of abstinence.
Falling stimulation contributes to withdrawal.
Irritability and concentration difficulty are withdrawal symptoms.
Smoking restores nicotine-related receptor activity.
Dopamine activity and normal functioning are temporarily restored.
Theo regulates his intake to prevent symptoms becoming severe.
Other Neurotransmitters and Chemicals
Dopamine is central to the AQA specification, but it is not the only chemical involved.
The November 2020 mark scheme also recognises:
Serotonin.
GABA.
Natural opioids such as endorphins and enkephalins.
The June 2021 mark scheme identifies the involvement of several neurotransmitters as an important evaluation of an explanation focused too narrowly on dopamine.
Natural Opioids
Endorphins and Enkephalins
Endorphins and enkephalins are naturally occurring opioid chemicals in the brain.
They are associated with:
Pleasure.
Pain regulation.
Feelings of wellbeing.
Nicotine may affect the release of these chemicals, contributing to pleasurable or calming effects.
This provides another possible neurochemical reason why smoking is reinforcing.
Why This Matters for Evaluation
If nicotine addiction involves dopamine and natural opioids, then a dopamine-only account is incomplete.
The wider explanation should be:
Nicotine alters interacting neurochemical systems, with dopamine playing a particularly important role in reward and reinforcement.
GABA
What Is GABA?
GABA is an inhibitory neurotransmitter.
Inhibitory neurotransmitters generally reduce the likelihood that receiving neurons will fire.
Nicotine may affect GABA-related control within reward pathways.
Changes in inhibitory and excitatory balance can alter dopamine-neuron activity.
For AQA examination purposes, students do not need to provide a highly technical molecular account.
The evaluative point is:
Dopamine activity is influenced by other chemical systems, so nicotine addiction cannot be reduced to one neurotransmitter acting alone.
Serotonin
What Is Serotonin?
Serotonin is involved in:
Mood.
Sleep.
Appetite.
Emotional regulation.
AQA’s November 2020 mark scheme recognises that nicotine may increase serotonin activity.
Serotonin-related effects might contribute to why some smokers report changes in:
Mood.
Anxiety.
Appetite.
Emotional state.
Again, this demonstrates the complexity of brain neurochemistry.
Applying the Full Neurochemical Explanation
Consider this scenario:
When Priya first started smoking, she felt relaxed and pleased after a cigarette. She now smokes much more frequently. If she goes several hours without nicotine, she becomes irritable and cannot concentrate. Smoking quickly makes her feel normal again.
Nicotinic receptors
Nicotine binds to nicotinic acetylcholine receptors within the reward system.
Dopamine
This increases dopamine release within the mesolimbic pathway, including the nucleus accumbens.
Positive reinforcement
Priya’s early feelings of pleasure and relaxation positively reinforce smoking.
Tolerance
Neurochemical adaptation means she now needs more frequent nicotine exposure.
Withdrawal
Irritability and concentration difficulty appear when nicotine levels fall.
Negative reinforcement
Smoking removes the unpleasant withdrawal state, reinforcing further use.
Physical dependence
Priya now smokes partly to restore expected neurochemical functioning and feel normal.
Initiation of Nicotine Use
Can Neurochemistry Explain the First Cigarette?
The neurochemical explanation can explain why an early experience of nicotine may be rewarding.
However, it may not fully explain why the person decided to smoke for the first time.
Initiation may be influenced by:
Peer pressure.
Family modelling.
Availability.
Curiosity.
Sensation seeking.
Social identity.
Cultural attitudes.
The person must first be exposed to nicotine before its neurochemical effects can reinforce behaviour.
A Balanced Initiation Explanation
A complete account might be:
Friends provide the opportunity to smoke.
The person conforms to gain approval.
Nicotine stimulates the reward pathway.
Dopamine-related reward reinforces the experience.
Repeated smoking produces adaptation and dependence.
Social influence explains exposure.
Neurochemistry explains why the behaviour becomes biologically rewarding and difficult to stop.
Maintenance of Nicotine Addiction
The neurochemical explanation is particularly effective at explaining maintenance.
Maintenance includes:
Continued use.
Increasing consumption.
Physical dependence.
Withdrawal.
Craving.
Relapse.
The explanation can account for why a smoker continues despite:
Knowing the health risks.
Wanting to quit.
Experiencing financial cost.
Receiving social disapproval.
Once dependence develops, smoking is reinforced by both reward and relief.
Neurochemistry and Cue Reactivity
Environmental cues may become associated with nicotine-related reward.
For example:
A morning coffee.
A work break.
A particular chair.
Alcohol.
Seeing a cigarette packet.
Meeting smoking friends.
The cue may activate expectations and craving even before nicotine is consumed.
Learning and neurochemistry therefore interact:
Cue activates learned expectation → reward pathway becomes engaged → craving occurs → nicotine is consumed → dopamine reward confirms the association
AQA’s June 2023 material recognises that cue reactivity is consistent with the neural basis of classical conditioning through reward pathways.
Neurochemistry and Genetic Vulnerability
Genes may influence:
Nicotinic receptor functioning.
Dopamine-receptor availability.
Nicotine metabolism.
Reward sensitivity.
Withdrawal severity.
This connects with inherited differences affecting addiction risk [Lesson 2: Genetic vulnerability].
A possible sequence is:
Genetic variation → altered receptor or dopamine functioning → nicotine is particularly reinforcing → increased vulnerability to dependence
Genes do not force the person to smoke.
Environmental exposure remains necessary.
Neurochemistry and Personality
Personality may influence exposure to nicotine.
For example:
Sensation seeking may increase experimentation.
Impulsivity may reduce consideration of health consequences.
Neuroticism may increase smoking for emotional relief.
Neurochemistry then explains why nicotine becomes rewarding and dependence develops.
The approaches answer different questions:
Personality explanation | Neurochemical explanation |
Why might the person experiment? | What does nicotine do within the brain? |
Why might immediate reward be attractive? | How is reward biologically produced? |
Why might someone use smoking to cope? | How can nicotine alter mood and reinforcement? |
Why might a person struggle with impulses? | Why do withdrawal and craving occur? |
Evaluating the Neurochemical Explanation
Strength: It Provides a Detailed Biological Mechanism
A major strength is that the explanation identifies a specific process.
It does not merely state that nicotine is pleasurable.
It explains:
Nicotine reaches the brain.
It binds to nicotinic acetylcholine receptors.
Dopamine neurons in the VTA are activated.
Dopamine is released in the nucleus accumbens.
The reward pathway is stimulated.
Smoking is reinforced.
Repeated exposure produces tolerance and dependence.
This detailed mechanism makes the explanation:
Testable.
Scientifically useful.
Relevant to treatment.
More precise than a vague biological claim.
Strength: Objective Biological Measurement
Researchers can investigate aspects of the explanation using:
Brain imaging.
Neurochemical measurement.
Receptor-binding techniques.
Animal studies.
Pharmacological manipulation.
Measures of withdrawal and craving.
These methods can produce quantitative data.
For example, researchers may compare:
Dopamine-related activity before and after nicotine.
Receptor availability in smokers and non-smokers.
Behaviour after a receptor is blocked.
Craving during abstinence.
Objective measurement reduces reliance on smokers accurately describing internal biological processes.
Limitation: Brain Activity Requires Interpretation
A brain scan or chemical measure does not explain itself.
Researchers must infer that:
Increased activity represents reward.
A measured difference relates to addiction.
The observed system caused the behaviour.
Two groups may differ in dopamine activity without the difference being the original cause of addiction.
The biological measure is objective, but its psychological interpretation may still be uncertain.
Strength: Evidence That Nicotine Affects the Reward Pathway
Research using biological measures consistently supports the general claim that nicotine interacts with nicotinic receptors and affects dopamine reward pathways.
This supports a central prediction of the explanation:
Nicotine use should be associated with measurable changes in systems involved in reward and motivation.
AQA’s 2025 assessment confirms that the required relationship is increased dopamine action, stimulation of the reward pathway and feelings of euphoria.
Limitation: Evidence May Show an Effect, Not Addiction
Showing that nicotine increases dopamine does not by itself explain:
Why one person becomes addicted.
Why another person smokes only occasionally.
Why some people stop successfully.
Why particular cues trigger relapse.
Why the person tried smoking initially.
The same acute chemical effect can occur without the person developing a persistent addiction.
The explanation therefore needs to include:
Repeated use.
Adaptation.
Tolerance.
Withdrawal.
Social and psychological differences.
Strength: The Explanation Accounts for Tolerance
Neuroadaptation provides a plausible explanation for increasing nicotine consumption.
Repeated receptor stimulation changes the system, so:
The previous dose becomes less effective.
Greater nicotine intake is required.
Smoking may become more frequent.
This links observable behaviour with an underlying biological process.
It also connects directly with the required characteristic of tolerance from describing addiction [Lesson 1: Describing addiction].
Strength: The Explanation Accounts for Withdrawal
The neurochemical approach explains why stopping smoking can produce genuine discomfort.
Withdrawal is not simply:
Weak willpower.
A preference.
A habit the person chooses not to break.
It reflects brain and bodily adaptation to repeated nicotine exposure.
This can reduce moral judgement and increase understanding of why quitting is difficult.
Strength: Practical Applications
A useful scientific explanation should lead to effective interventions.
The neurochemical account suggests that treatment might:
Replace nicotine more safely.
Stimulate nicotinic receptors without smoking.
Block nicotine’s rewarding effects.
Reduce craving.
Ease withdrawal.
Alter neurotransmitter activity.
These principles underpin medication based on biological explanations of addiction [Lesson 8: Drug therapy].
The success of biologically based treatments would provide indirect support for the explanation.
Treatment Success Is Not Complete Proof
Even where a medication reduces craving, this does not prove that neurochemistry was the only cause of addiction.
Treatment might help one part of the addiction while leaving:
Smoking cues.
Social routines.
Stress.
Beliefs.
Peer influence.
Motivation.
A treatment can work without confirming a complete explanation.
Limitation: Dopamine Reductionism
A dopamine-only explanation is biologically reductionist.
It reduces nicotine addiction to:
Receptors.
Dopamine neurons.
Reward pathways.
Neurochemical adaptation.
This has advantages because these components can be:
Operationalised.
Measured.
Manipulated.
Used to design treatment.
However, it may ignore:
Social learning.
Peer pressure.
Stress.
Personality.
Cognitive expectations.
Environmental cues.
Individual meaning.
The June 2021 mark scheme specifically identifies the involvement of GABA and serotonin as evidence that the neurochemical process is more complex than dopamine alone.
A More Accurate Biological Conclusion
Rather than stating:
Dopamine causes nicotine addiction.
A better conclusion is:
Dopamine is an important part of a wider neurochemical system through which nicotine reward, motivation and dependence are produced.
Limitation: Other Neurochemicals Are Involved
Nicotine affects more than dopamine.
Relevant systems include:
Acetylcholine.
Natural opioids.
GABA.
Serotonin.
These systems influence one another.
Therefore:
Dopamine changes may depend on other neurotransmitters.
Mood effects may involve serotonin.
Pleasure may involve endogenous opioids.
Inhibitory control may involve GABA.
The explanation becomes more realistic but also more complex.
A single-transmitter theory may lack explanatory power.
Limitation: Cause and Effect
A relationship between dopamine functioning and nicotine addiction does not automatically establish causation.
Possible explanations include:
Atypical dopamine functioning increases addiction risk.
Repeated nicotine exposure changes dopamine functioning.
Both processes occur.
Genetic differences affect both.
Stress or another factor influences both.
Human participants cannot ethically be assigned to develop long-term nicotine addiction.
This limits experimental control.
The June 2021 AQA mark scheme identifies problems demonstrating cause and effect as a central evaluation issue.
Animal Research
Advantages
Animal research may allow scientists to:
Control nicotine exposure.
Manipulate receptors.
Measure neurochemical activity directly.
Use comparison groups.
Investigate cause and effect.
This can produce stronger causal evidence than correlational human research.
Limitations
Animal findings may not generalise fully to human smoking because humans experience:
Social pressure.
Complex beliefs.
Cultural meanings.
Long-term goals.
Self-awareness.
Learned smoking rituals.
An animal can demonstrate nicotine reinforcement without reproducing the full psychological and social experience of cigarette addiction.
Ethical Issues
Animal studies may involve:
Repeated drug exposure.
Dependence.
Withdrawal.
Invasive procedures.
Harm or distress.
The scientific value must be weighed against ethical costs.
AQA’s June 2021 mark scheme recognises ethical difficulty in experimental research on nicotine addiction.
Limitation: Initiation Is Not Fully Explained
The neurochemical explanation cannot act until nicotine enters the body.
It therefore cannot completely explain:
Why a person first accepts a cigarette.
Why smoking is available.
Why friends approve.
Why a person identifies with smokers.
Why smoking is culturally normalised.
The explanation may be strongest for:
Reward after initial use.
Maintenance.
Tolerance.
Withdrawal.
Relapse.
It is weaker as a complete explanation of initiation.
Strength: Maintenance Is Explained Well
Once dependence develops, the approach explains a powerful cycle:
Nicotine reward → repeated use → adaptation → falling nicotine levels → withdrawal → renewed smoking
This explains why smoking may continue after:
The novelty disappears.
The person wants to stop.
Pleasure has weakened.
Health warnings are understood.
AQA’s June 2021 mark scheme encourages evaluation of whether explanations account for different stages of addiction, including initiation and maintenance.
Limitation: Individual Differences
Not everyone exposed to nicotine becomes addicted.
Smokers differ in:
Frequency of smoking.
Speed of tolerance.
Severity of withdrawal.
Reward response.
Ability to stop.
Sensitivity to medication.
Craving.
These differences suggest roles for:
Genes.
Personality.
Social environment.
Learning history.
Stress.
Motivation.
A universal dopamine sequence may describe a common mechanism without explaining all individual variation.
Limitation: Mediating Variables
A mediating variable helps explain how or why one factor affects another.
Possible mediators between nicotine exposure and addiction include:
Childhood experiences.
Education.
Peer groups.
Family attitudes.
Stress.
Expectations.
Self-efficacy.
The June 2021 mark scheme identifies social variables such as childhood experience and education as factors that may mediate biological influence.
For example:
Nicotine may be biologically rewarding, but a strong anti-smoking environment may prevent repeated exposure and therefore prevent dependence.
Interaction with Learning Theory
The neurochemical and learning explanations are not necessarily competitors.
They may describe different levels of the same process.
Neurochemical level
Nicotine activates receptors.
Dopamine activity increases.
Reward is experienced.
Learning level
The rewarding consequence reinforces smoking.
Environmental cues become associated with nicotine.
Craving is conditioned.
Smoking removes withdrawal.
The biological effect provides the reward that operant and classical conditioning act upon.
A complete account may be:
Nicotine produces dopamine-related reward, and the person learns to repeat smoking and respond to associated cues.
Interaction with Social Influence
Social factors may determine:
Whether nicotine is available.
Whether smoking is modelled.
Whether participation receives approval.
Which situations contain smoking cues.
Neurochemistry determines part of what happens after nicotine is consumed.
For example:
Friends offer a cigarette.
The person conforms.
Nicotine stimulates dopamine activity.
The effect is rewarding.
Friends also provide social approval.
Both biological and social reinforcement encourage repetition.
Interaction with Genetic Vulnerability
Inherited variation may affect:
Nicotinic receptors.
Dopamine receptors.
Nicotine metabolism.
Withdrawal severity.
This means the same nicotine exposure may produce different effects in different people.
The neurochemical explanation therefore works well alongside genetic vulnerability.
Biological Determinism
The explanation may be criticised as biologically deterministic because it suggests that chemical processes govern smoking.
A strongly deterministic interpretation might imply:
Once nicotine changes the reward system, the smoker has no meaningful control.
This is too extreme because:
Many smokers quit.
Treatment can help.
Social circumstances matter.
Coping skills can be learned.
People can avoid cues.
Motivation changes behaviour.
A more balanced interpretation is soft determinist:
Neurochemical processes place strong constraints on behaviour, but conscious strategies and environmental support can increase control.
Socially Sensitive Implications
A neurochemical explanation may reduce stigma by presenting addiction as involving genuine biological dependence rather than moral weakness.
This can:
Encourage treatment.
Increase empathy.
Reduce blame.
Improve access to healthcare.
However, it could also:
Encourage a belief that recovery is impossible.
Reduce perceived personal agency.
Lead to overreliance on medication.
Ignore social inequalities contributing to smoking.
Shift attention away from prevention.
The explanation should therefore be communicated as biological influence rather than biological destiny.
Parsimony
A biological explanation is relatively parsimonious because it explains complex behaviour through a limited number of mechanisms.
The sequence involving:
Nicotinic receptors.
Dopamine.
Reward.
Tolerance.
Withdrawal.
is clear and efficient.
However, an explanation can be too simple.
Parsimony becomes a weakness if important social, cognitive and learning influences are omitted.
Scientific Status
The neurochemical explanation contributes to Psychology’s scientific status because it involves:
Measurable variables.
Biological mechanisms.
Objective equipment.
Testable predictions.
Replicable procedures.
Treatment applications.
However, scientific measurement does not guarantee that the explanation is complete.
A precise biological description may still explain only one level of a multidimensional addiction.
Practical Implications for Prevention
A neurochemical understanding may inform prevention by explaining that:
Nicotine quickly affects reward systems.
Repeated exposure can produce adaptation.
Occasional use may escalate.
Withdrawal can make stopping difficult.
Early avoidance prevents dependence from developing.
This challenges the belief:
“I can smoke regularly and stop whenever I choose.”
It also explains why early intervention may be valuable.
Overall Evaluation
Brain neurochemistry provides a detailed and scientifically testable explanation of nicotine addiction. Nicotine acts as an agonist at nicotinic acetylcholine receptors, increasing the activity of dopamine neurons in the ventral tegmental area. Dopamine is then released in the nucleus accumbens, stimulating the mesolimbic reward pathway. The resulting reward positively reinforces smoking.
Repeated nicotine exposure changes receptor and neurotransmitter functioning. The original dose becomes less effective, producing tolerance, while falling nicotine levels create withdrawal and craving. Smoking then restores stimulation and removes discomfort, maintaining dependence.
The explanation is supported by objective biological evidence and has useful implications for drug treatment. It is particularly successful at explaining maintenance, tolerance and withdrawal.
However, dopamine is only one part of a more complex system involving acetylcholine, GABA, serotonin and endogenous opioids. Human research has difficulty establishing cause and effect, while animal studies may not generalise to socially complex human smoking. The explanation also struggles to explain why the first cigarette is tried.
The most convincing conclusion is interactionist: neurochemistry explains the powerful biological reward and dependence produced by nicotine, while genes, personality, learning, cues and social environments influence exposure and individual outcomes.
Key Words 🔑
Key word | Student-friendly definition | How it may be used in an exam |
Brain neurochemistry | Chemical processes through which brain cells communicate and regulate behaviour | Introduce the biological explanation |
Neuron | A specialised cell that transmits information in the nervous system | Explain brain communication |
Synapse | The gap between two neurons across which chemical communication occurs | Explain neurotransmission |
Neurotransmitter | A chemical messenger released by a neuron | Define dopamine and acetylcholine |
Receptor | A specialised structure to which a neurotransmitter or drug can bind | Explain nicotine’s action |
Acetylcholine | A neurotransmitter involved in arousal, attention and other functions | Identify the natural transmitter at nicotinic receptors |
Nicotinic acetylcholine receptor | A receptor activated by acetylcholine and nicotine | Explain the starting point of nicotine action |
Agonist | A chemical that binds to and activates a receptor | Explain nicotine’s effect |
Reward system | Brain structures involved in motivation, pleasure and reinforcement | Explain why smoking is repeated |
Mesolimbic pathway | A dopamine pathway involved in reward and motivation | Name the relevant neural pathway |
Ventral tegmental area | A brain area containing dopamine-producing neurons involved in reward | Explain where nicotine activates dopamine neurons |
Nucleus accumbens | A reward-related structure receiving dopamine projections from the VTA | Explain where dopamine activity increases |
Dopamine | A neurotransmitter involved in reward, motivation and reinforcement | Explain nicotine’s rewarding effect |
Euphoria | An intense or elevated feeling of pleasure or wellbeing | Describe one possible effect of reward-pathway activation |
Positive reinforcement | Behaviour increasing because it produces a rewarding consequence | Explain pleasure maintaining smoking |
Negative reinforcement | Behaviour increasing because it removes an unpleasant condition | Explain relief from withdrawal |
Neuroadaptation | Changes in brain functioning following repeated substance exposure | Explain dependence and tolerance |
Homeostasis | Maintenance of a relatively stable internal state | Explain the brain’s compensation for nicotine |
Desensitisation | A reduction in receptor responsiveness after repeated stimulation | Explain one contribution to tolerance |
Tolerance | Needing more nicotine to produce the previous effect | Explain increasing consumption |
Physical dependence | Physiological adaptation that makes nicotine appear necessary for normal functioning | Explain withdrawal |
Withdrawal syndrome | Physical and psychological symptoms appearing when nicotine is reduced or stopped | Explain motivation to resume smoking |
Craving | A powerful urge to use nicotine | Explain relapse and maintenance |
Nicotine regulation model | The idea that dependent smokers regulate nicotine intake to avoid withdrawal | Explain repeated smoking across the day |
Natural opioids | Brain chemicals such as endorphins and enkephalins associated with pleasure | Show that dopamine is not the only chemical involved |
GABA | An inhibitory neurotransmitter that influences neural activity | Evaluate dopamine reductionism |
Serotonin | A neurotransmitter involved in mood, appetite and sleep | Explain wider neurochemical effects |
Initiation | The beginning of addictive behaviour | Evaluate the explanation’s limited account of first use |
Maintenance | The continuation of addictive behaviour | Explain where neurochemistry is strongest |
Relapse | Returning to smoking after an attempt to stop | Explain the effects of craving and withdrawal |
Biological reductionism | Explaining behaviour mainly through biological components | Evaluate the narrow focus |
Biological determinism | The view that biological processes govern behaviour | Evaluate personal control |
Mediating variable | A factor influencing how one variable affects another | Explain social or psychological influences |
Interactionism | The view that biological and environmental factors operate together | Reach a balanced conclusion |
Hints from the Examiner Reports 💡
Follow the Full Biological Sequence
Examiner hint: Avoid writing only:
Nicotine releases dopamine and feels good.
A developed answer should include:
Nicotine binds to nicotinic acetylcholine receptors.
The receptors are associated with the ventral tegmental area.
Dopamine neurons become more active.
Dopamine is released in the nucleus accumbens.
The mesolimbic reward pathway is stimulated.
Reward reinforces smoking.
The November 2020 mark scheme identifies each of these elements as relevant description.
Use the Correct Direction of Dopamine Activity
AQA’s June 2025 question tested whether students understood the exact direction of the effect.
The correct sequence is:
Nicotine increases dopamine action, stimulating the reward pathway and producing feelings of euphoria.
Do not write that nicotine:
Reduces dopamine.
Inhibits the reward pathway.
Blocks all dopamine receptors.
Prevents pleasure.
Do Not Call Nicotine a Neurotransmitter
Nicotine is an external chemical that acts as an agonist at nicotinic acetylcholine receptors.
Dopamine and acetylcholine are neurotransmitters.
Distinguish the Brain Structures
Use the terms accurately:
VTA: Contains dopamine-producing neurons.
Nucleus accumbens: Receives dopamine within the reward pathway.
Mesolimbic pathway: The wider reward pathway connecting relevant structures.
Avoid describing all three as the same place.
Include Tolerance and Withdrawal
A complete six-mark description should not stop after dopamine-related pleasure.
Add:
Repeated receptor stimulation.
Neuroadaptation.
Greater nicotine required for the same effect.
Falling nicotine levels.
Withdrawal and craving.
Renewed motivation to smoke.
Match the Command Word
The November 2020 examiner report noted that the six-mark questions in Section D required description only and that some students wasted time by offering evaluation.
For describe:
Give accurate AO1.
Explain the process in sequence.
Use specialist terminology.
Do not spend time evaluating.
For describe and evaluate:
Explain the neurochemical process.
Then include evidence, complexity, causality, stages and alternative factors.
Use Specialist Terminology Precisely
Strong terminology includes:
Agonist.
Nicotinic acetylcholine receptor.
Ventral tegmental area.
Nucleus accumbens.
Mesolimbic pathway.
Dopamine.
Positive reinforcement.
Neuroadaptation.
Tolerance.
Withdrawal.
A long answer using vague language such as “happy chemicals” is weaker than a shorter, precise answer.
Do Not Overclaim Dopamine
A better statement is:
Dopamine contributes to reward, motivation and reinforcement.
Avoid:
Dopamine is addiction.
or:
Dopamine is the only chemical involved.
The June 2021 mark scheme specifically rewards evaluation recognising the roles of GABA and serotonin.
Explain the Stage of Addiction
When evaluating, ask:
Does the explanation account for initiation?
Does it explain maintenance?
Does it explain withdrawal?
Does it explain relapse?
The neurochemical account is generally more effective for maintenance than for explaining why smoking first begins.
Develop Cause and Effect
Do not write only:
The evidence is correlational.
Develop the problem:
Dopamine differences found among dependent smokers may have resulted from repeated nicotine use rather than causing the addiction. Ethical restrictions prevent researchers assigning people to prolonged nicotine exposure, making direction of causation difficult to establish.
Use Animal Evidence Carefully
Animal experiments may allow:
Greater control.
Receptor manipulation.
Stronger causal conclusions.
However, animals do not reproduce:
Human peer influence.
Expectations.
Cultural attitudes.
Smoking rituals.
Complex conscious motivation.
Link Biology and Learning
A strong interactionist point is:
Dopamine provides the rewarding biological consequence, while operant conditioning explains why the consequence increases smoking. Classical conditioning then explains why environmental cues trigger craving.
This creates a more complete explanation without losing the question’s neurochemical focus.
Avoid Invented Research Evidence
The supplied AQA mark schemes identify the types of evidence that may be used but do not provide detailed named neurochemical studies or exact numerical findings.
Do not invent:
Sample sizes.
Dopamine percentages.
Brain-scan findings.
Researchers’ names.
Follow-up periods.
Accurate explanation and developed methodological evaluation are safer than fabricated evidence.
Common Mistakes ⚠️
Mistake 1
Mistake: Saying nicotine is a neurotransmitter.
Why this is incorrect:
Nicotine is an external chemical that binds to neurotransmitter receptors.
How to improve:
State that nicotine acts as an agonist at nicotinic acetylcholine receptors.
Mistake 2
Mistake: Saying nicotine binds directly to dopamine receptors.
Nicotine primarily binds to nicotinic acetylcholine receptors, which then affect dopamine-neuron activity.
How to improve:
Explain the receptor-to-dopamine sequence.
Mistake 3
Mistake: Saying dopamine is released by the nucleus accumbens.
Why this is inaccurate:
Dopamine neurons originating in the VTA project to and release dopamine within the nucleus accumbens.
How to improve:
Identify the direction of the pathway.
Mistake 4
Mistake: Saying nicotine decreases dopamine.
Why this contradicts the required explanation:
Nicotine increases dopamine action in the reward pathway.
How to improve:
Use the sequence: increased dopamine, stimulated reward pathway, rewarding effect.
Mistake 5
Mistake: Calling dopamine the pleasure chemical without further explanation.
Why this is too simplistic:
Dopamine is also involved in motivation, learning and reward seeking.
How to improve:
Explain how dopamine reinforces behaviour and increases motivation to repeat smoking.
Mistake 6
Mistake: Explaining only pleasure.
Why this is incomplete:
A complete explanation includes tolerance, withdrawal and craving.
How to improve:
Describe both positive reinforcement and smoking to remove withdrawal.
Mistake 7
Mistake: Saying positive reinforcement means that smoking is good.
Why this is incorrect:
Positive means that a consequence is added, not that it is healthy.
How to improve:
State that a rewarding effect is added and smoking becomes more likely.
Mistake 8
Mistake: Saying negative reinforcement is punishment.
Why this is incorrect:
Negative reinforcement increases smoking because withdrawal is removed.
How to improve:
Remember:
Reinforcement increases behaviour. Negative means removal.
Mistake 9
Mistake: Confusing tolerance with withdrawal.
Why this is incorrect:
Tolerance occurs during repeated use. Withdrawal occurs when nicotine use decreases.
How to improve:
Use the timing of the experience.
Mistake 10
Mistake: Saying tolerance means the smoker can tolerate nicotine better and therefore needs less.
Why this is incorrect:
The smoker needs more nicotine to obtain the same effect.
How to improve:
Use the phrase “greater amount for the previous effect”.
Mistake 11
Mistake: Saying neurochemistry fully explains the first cigarette.
Why this is incomplete:
Nicotine cannot affect the reward pathway until it has been consumed.
How to improve:
Use social influence, personality or availability to explain initial exposure.
Mistake 12
Mistake: Saying every person exposed to nicotine becomes addicted.
Why this is incorrect:
People differ in biology, learning, exposure and social context.
How to improve:
Treat the effects as increasing likelihood rather than determining addiction.
Mistake 13
Mistake: Writing about cue reactivity instead of neurochemistry.
Why this loses focus:
Cue reactivity is part of the learning explanation.
How to improve:
Mention cues only when comparing or explaining an interaction with dopamine reward.
Mistake 14
Mistake: Using genetic evidence without a neurochemical link.
Why this is incomplete:
A genetic point is relevant only where it explains inherited differences in receptors, metabolism or dopamine functioning.
How to improve:
State the biological pathway clearly.
Mistake 15
Mistake: Using “reductionist” as an unexplained label.
Why this is incomplete:
The examiner needs the consequence of reductionism.
How to improve:
Explain that focusing on dopamine may overlook GABA, serotonin, learning, stress, personality and social influence.
Exam-Style Questions ✍️
Question 1
Which one of the following best describes the role of dopamine in nicotine addiction?
A Nicotine decreases dopamine activity and inhibits the reward pathway.B Nicotine increases dopamine activity and stimulates the reward pathway.C Dopamine prevents nicotine from binding to acetylcholine receptors.D Dopamine causes nicotine to be removed from the brain.
[1 mark]
Question 2
What is meant by a neurotransmitter? [2 marks]
Question 3
Explain how nicotine affects nicotinic acetylcholine receptors. [3 marks]
Question 4
Outline the roles of the ventral tegmental area and nucleus accumbens in nicotine addiction. [4 marks]
Question 5
Zain says:
“When I first started smoking, a cigarette made me feel relaxed and pleased. Now I smoke much more often. If I go several hours without smoking, I become irritable and cannot concentrate. A cigarette makes me feel normal again.”
Use your knowledge of brain neurochemistry to explain Zain’s nicotine addiction. [6 marks]
Question 6
Explain how neurochemical adaptation may produce tolerance and withdrawal in nicotine addiction. [4 marks]
Question 7
Explain one difference between the neurochemical explanation and learning theory as explanations for nicotine addiction. [4 marks]
Question 8
A researcher recorded an index of dopamine-related activity before and after participants received nicotine.
Condition | Mean dopamine-activity index |
Before nicotine | 80 |
After nicotine | 116 |
Calculate the percentage increase in the dopamine-activity index. Explain how the result relates to the neurochemical explanation of nicotine addiction. [4 marks]
Question 9
Explain one strength and one limitation of the neurochemical explanation of nicotine addiction. [6 marks]
Question 10
Describe and evaluate brain neurochemistry as an explanation for nicotine addiction. [16 marks]
Answers and Mark Scheme
Question 1
Answer: B
Nicotine increases dopamine activity and stimulates the reward pathway. [1 mark]
Question 2
Award one mark for each of the following:
A neurotransmitter is a chemical messenger released by a neuron.
It crosses a synapse and affects a receiving neuron by binding to receptors.
Maximum: 2 marks
Question 3
Award one mark for each linked point, up to three marks:
Nicotine reaches the brain after being consumed.
It binds to nicotinic acetylcholine receptors.
Nicotine acts as an agonist and activates the receptors.
This increases activity in neurons connected with the reward pathway.
Dopamine release is consequently increased.
Question 4
Award up to two marks for the VTA:
The ventral tegmental area contains dopamine-producing neurons.
Nicotine activates nicotinic receptors within or connected to this system.
Dopamine-neuron activity increases.
Award up to two marks for the nucleus accumbens:
VTA neurons project to the nucleus accumbens.
Dopamine is released within the nucleus accumbens.
This stimulates reward and reinforces smoking.
Question 5
Award up to six marks for effective application:
Nicotine binds to nicotinic acetylcholine receptors.
This activates dopamine neurons in the VTA.
Dopamine is released in the nucleus accumbens.
Zain’s early pleasure or relaxation positively reinforced smoking.
Repeated nicotine exposure caused neuroadaptation.
Smoking more frequently suggests tolerance.
Irritability and poor concentration are withdrawal symptoms.
Falling nicotine levels reduce accustomed receptor stimulation.
Smoking restores nicotine and dopamine-related activity.
Feeling normal again removes withdrawal.
Relief negatively reinforces continued smoking.
The process indicates physical dependence.
A full-mark response should connect the scenario with both reward and dependence.
Question 6
Award up to two marks for tolerance:
Repeated nicotine stimulation changes receptor or neurotransmitter functioning.
The original amount produces a weaker effect.
More nicotine is needed to obtain the previous reward or relief.
Award up to two marks for withdrawal:
The brain has adapted to the presence of nicotine.
When nicotine levels fall, accustomed receptor stimulation and reward activity decrease.
Craving, irritability or other symptoms appear.
Smoking restores stimulation and reduces the symptoms.
Question 7
Possible answer:
The neurochemical explanation focuses on biological processes. Nicotine activates nicotinic acetylcholine receptors and increases dopamine activity in the mesolimbic reward pathway. Learning theory focuses on how the resulting pleasure or relief reinforces smoking and how environmental cues become associated with nicotine. Neurochemistry therefore explains the biological reward, whereas learning theory explains how experience and association shape repeated smoking.
For four marks:
Both explanations should be accurate.
A direct distinction should be made.
The explanations may also be described as complementary.
Question 8
Award up to two marks for the correct calculation:
Increase=116−80=36Percentage increase=8036×100=45%
The dopamine-activity index increased by 45%.
Award up to two marks for explanation:
The increase is consistent with nicotine increasing dopamine action.
Greater dopamine activity may stimulate the reward pathway.
Reward may positively reinforce nicotine use.
The data alone do not demonstrate that the dopamine increase caused long-term addiction.
Question 9
Award up to three marks for one developed strength and up to three marks for one developed limitation.
Possible strength:
The explanation provides a detailed, testable biological mechanism. Researchers can measure receptor and dopamine-related activity before and after nicotine exposure. Evidence that nicotine activates the reward pathway supports the claim that smoking is biologically reinforcing. The explanation has also led to drug treatments targeting craving and withdrawal.
Possible limitation:
The explanation may be biologically reductionist because it focuses heavily on dopamine. Nicotine also affects acetylcholine, GABA, serotonin and natural opioids, while social pressure, stress and conditioned cues influence smoking. Dopamine therefore provides only one level of a more complex explanation.
Other creditworthy limitations include:
Difficulty establishing cause and effect.
Ethical problems in experimental research.
Problems generalising animal studies.
Better explanation of maintenance than initiation.
Individual differences.
Biological determinism.
Question 10
A high-level response should include accurate knowledge and developed evaluation.
Indicative AO1 content
Brain neurochemistry.
Neurons, synapses and neurotransmitters.
Acetylcholine.
Nicotinic acetylcholine receptors.
Nicotine acting as an agonist.
Ventral tegmental area.
Dopamine-producing neurons.
Nucleus accumbens.
Mesolimbic reward pathway.
Increased dopamine activity.
Feelings of reward, pleasure or reduced anxiety.
Positive reinforcement.
Repeated receptor activation.
Neuroadaptation.
Desensitisation or altered receptor functioning.
Tolerance.
Nicotine regulation.
Abstinence.
Withdrawal.
Craving.
Negative reinforcement.
Natural opioids.
Possible roles of GABA and serotonin.
Possible genetic influences on receptor functioning.
Indicative AO3 content
Detailed and testable biological mechanism.
Objective measures of receptors and brain activity.
Evidence that nicotine affects dopamine reward pathways.
Explanation of tolerance and withdrawal.
Practical applications for drug therapy.
Treatment success as indirect support.
Dopamine reductionism.
Other neurotransmitters and natural opioids.
Complex interactions among brain systems.
Cause-and-effect problems.
Nicotine use possibly changing dopamine systems.
Ethical difficulty of human experiments.
Greater experimental control in animal research.
Problems generalising animal findings.
Better explanation of maintenance than initiation.
Social learning and peer influence explaining first exposure.
Cue reactivity interacting with reward pathways.
Individual differences.
Genetic vulnerability.
Mediating social and psychological variables.
Biological determinism.
Positive implications for reducing blame.
Risk of reducing perceived personal control.
Need for a biopsychosocial or interactionist account.
Thirteen to sixteen marks: Knowledge is accurate and generally detailed. The biological sequence is explained clearly from nicotinic receptors to dopamine reward, tolerance and withdrawal. Evaluation is thorough and focused, using issues such as neurochemical complexity, causality, initiation versus maintenance and interaction with learning. Specialist terminology is used precisely.
Nine to twelve marks: Knowledge is mostly accurate and evaluation is generally effective. The main reward pathway and dopamine are explained, although some biological detail or evaluative arguments may lack development.
Five to eight marks: Some relevant knowledge is present, but the response is mainly descriptive. Dopamine may be mentioned without a clear account of receptors, structures, tolerance or withdrawal. Evaluation may be generic.
One to four marks: Knowledge is very limited or confused. The response may state only that smoking releases a pleasure chemical, incorrectly describe dopamine activity or provide little relevant evaluation.
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