Drug Use and Society (Edexcel A-Level Psychology): Revision Notes

Theories of Addiction

Addiction develops when a person carries on using drugs despite negative consequences. This occurs due to physiological and psychological changes resulting from substance use. Two key approaches help explain why people become addicted: biological explanations (focusing on neurotransmitter changes) and learning explanations (examining how behaviour is acquired and maintained).

Biological explanation: the role of neurotransmitters

Biological explanations suggest that key physiological influences within the body make it more likely that a person will engage in substance use and develop dependency and withdrawal. These explanations form the 'nature' side of the nature-nurture debate regarding addiction.

How drugs affect the brain

Drugs create one of two reactions in the brain through their effect on neurotransmitter availability. They affect the body by having either an agonist role or an antagonist role, and can also act as reuptake inhibitors. The way in which a drug changes the anatomy or function of a cell is known as the 'mode of action'.

Agonists are drugs that mimic neurotransmitters. They fit onto receptor sites, making the post-synaptic dendrite believe that the drug is a neurotransmitter. This makes the neuron fire. Substances that act as agonists make the stimulation of one neuron by another much easier. Using stimulants can result in temporary alertness and increased levels of energy, though it can also create an increased body temperature and an irregular heartbeat. Both heroin and nicotine are agonist substances.

Antagonists are drugs that bind onto receptor sites on a neuron and prevent it from firing. This prevents the message being passed from neuron to neuron. Substances may act as a depressant and will slow the brain's activity down. As brain activity is reduced, the transmission of messages between neurons becomes less effective. Alcohol is considered to be a depressant, which can result in poor concentration, sluggish behaviour, confusion and slurred speech.

Reuptake inhibitors are drugs that work by binding onto the axon terminal branches. This prevents the axon terminal from taking up the neurotransmitter left over in the synapse, causing an excess of that neurotransmitter. For example, cocaine is a reuptake inhibitor for the neurotransmitter dopamine. When the axon terminal cannot take up the leftover dopamine, and the dendrite from the next neuron has reached its threshold, we are left with too much dopamine, causing the stimulating effects of cocaine.

Alcohol

Alcohol is consumed in liquid form. The type of alcohol found in alcoholic drinks is called ethanol, made from plant material. Grains, fruit or vegetables are processed and allowed to ferment for differing amounts of time, which affects how much ethanol is in the drink. Alcohol is legal in Britain for individuals over the age of 18 years.

Psychological effects

Alcohol reduces inhibitions as it targets the social control areas of the brain. Reduced effectiveness of these inhibitory mechanisms leads initially to relaxed, confident behaviour but can develop into exhibitionism and extreme behaviour at higher levels. Users may experience relaxation following a drink, which makes continued drinking more appealing. People who drink alcohol to avoid worrying about personal problems may find that the reduction in stress is positive, and they start to use alcohol as a way of coping with stress and worries. With increased use, the alcoholic becomes psychologically dependent on the alcohol, as they see it, albeit inaccurately, as a way out of their problems.

Physical effects

Initially, following a low intake of alcohol, users will feel warm and look flushed as a result of the alcohol causing blood vessels to dilate. The effect of alcohol on GABA (an inhibitory neurotransmitter) becomes noticeable as reactions to situations slow down. Alcohol also affects speech, making it more difficult to form coherent words. As the frontal lobes become more depressed, users will show less control over motor skills or coordination. Dehydration occurs when the alcohol inhibits the hormone controlling urination, so as alcohol levels start to fall, there is increased urination.

Long-term health problems can result from alcohol misuse. Key issues include liver disease and nerve damage. The brain can also be permanently affected. Some individuals may develop Korsakoff's syndrome, a brain disorder associated with heavy alcohol use that is characterised by short-term memory loss and potential changes to their personality. Pregnant women are advised not to drink alcohol during pregnancy, as this increases the risk of foetal abnormality.

Mode of action

Alcohol affects neurotransmission in various ways, including GABA receptors, and reduces serotonin activity. Serotonin is associated with emotions. A low level of serotonin in the brain can create feelings of depression. Alcohol is considered a depressant as it reduces serotonin levels and can make the person feel low in mood.

Alcohol also makes GABA more effective. GABA is an inhibitory neurotransmitter that makes it difficult for messages to be transmitted from one synapse to another. The presence of alcohol further slows down the speed at which messages are passed between neurons. This includes slowing down fight or flight reflexes that are usually triggered by noradrenaline synapses. The nerve endings of these noradrenalin synapses are numbed by the alcohol so are less effective. It also makes inhibitory systems of the brain less effective, so people under the influence of alcohol are likely to take more risks than they would do when sober.

Tolerance

Short-term tolerance can develop quickly, leading to people feeling more sober than they actually are when their blood alcohol levels drop slightly. This often contributes to behaviours such as people believing they are safe to drive a car after drinking alcohol.

Withdrawal

Withdrawal can be felt as early as two hours after the last drink, depending on the amount consumed. It is typically experienced 6-12 hours afterwards. Symptoms may include shaky hands, nausea, vomiting, headaches or insomnia. There may be some vivid dreaming or visual or tactile hallucinations that usually end within 48 hours.

Heroin

Heroin, or diacetylmorphine, is an opioid analgesic found naturally in the opium poppy. Historically, it has been used legally as a form of pain relief in the form of morphine. It is also used as an illegal recreational drug in which users aim to seek feelings of euphoria following consumption. Heroin is a highly addictive drug.

Psychological effects

Heroin rapidly produces a feeling of euphoria. The analgesic effect gives a feeling of calm and aches or pains will disappear. The intensity of the euphoria and well-being experienced by the user depends on the amount of heroin that has been taken. It is this feeling that acts as a reinforcement or motivator to use heroin again in the future.

Physical effects

The user will also feel their skin become warm, experience a dry mouth and their limbs may feel heavy. There is often a feeling of nausea or actual vomiting. As the amount of heroin builds up, they will experience nausea and vomiting on a less frequent basis, as it depresses the part of the brain associated with this action. A person's heart rate and breathing will slow down, often to life-threatening levels. This is because it changes the activity of neurochemicals in the brain stem, which is where automatic functions, including breathing and heart rate, are controlled. Mental functioning will become less clear and they will feel drowsy for a number of hours once the initial euphoria has faded.

Mode of action

Heroin attaches to receptors that would typically receive input from endorphins. During everyday activity, a moderate amount of endorphins is naturally produced, causing the release of dopamine and facilitating the reward systems within the brain. If the body is put under stress and pain, receptors are stimulated and the level of endorphins is increased. These lock onto the receptor sites that transmit information about pain, blocking the brain's ability to register pain.

Heroin acts like a massive release of endorphin into the brain. Once heroin has been taken, it quickly hydrolyses into morphine, which binds to opioid receptors concentrated in the reward pathway (ventral tegmental area, nucleus accumbens and cortex) and pain pathway (thalamus, brain stem and spinal cord) of the brain. This is the opiate that attaches to the opioid receptors on the post-synaptic membrane.

Tolerance

Repeated use of heroin can create long-term chemical imbalances in the brain that are not easily reversed. The brain adapts to the high levels of dopamine caused by the drug and down-regulates its own natural production of it. This means that the baseline measure of dopamine is now lower than before, so in order to get the same 'high', the user now needs more dopamine and so more of the drug. This results in a tolerance for the drug, where the user has to increase the amount they use in order to experience the same initial euphoria. The neural changes that have occurred due to repeated exposure to heroin mean that these areas of the brain will only function normally in the presence of the drug, which creates dependency.

Withdrawal

Withdrawal may occur within a few hours of taking heroin. How quickly withdrawal symptoms are experienced directly relates to the level of use; the more a person uses, the quicker and more intense the withdrawal symptoms will be. A person may become agitated if they are unable to take any heroin when experiencing withdrawal symptoms. Withdrawal can be very painful and may include symptoms such as muscle and bone pain, insomnia, cold flashes and restlessness. Symptoms will peak 24-48 hours after the last dose of heroin, and can last up to a week. The symptoms will gradually subside as the level of drug in the body reduces.

Nicotine

Nicotine is a nitrogen-containing chemical, made from plants, mainly the tobacco plant. It can also be produced synthetically. Nicotine is included in cigarettes, which are then smoked. It can also be used as an insecticide, so is not just for human consumption.

Psychological effects

Nicotine makes the smoker feel very relaxed as soon as they inhale the drug. This makes smoking a pleasurable experience, and stimulates the reward system, making the smoker want to continue smoking. The reduction in stress experienced when smoking creates a psychological dependency. This is in part due to the fact that nicotine deprivation can be stressful in itself, and is relieved as soon as the person smokes again.

Physical effects

Nicotine is highly addictive. The effect of nicotine on the body is almost instant, as it quickly enters the brain's blood supply. Drug levels peak within 7-10 seconds of inhalation, creating a sense of relaxation. The acute effects of nicotine reduce within a few minutes, causing the need to continue repeated intake throughout the day. As the dopamine reward system is stimulated, smoking creates a positive feeling in the smoker. This happens with each inhalation of smoke, so is continually rewarding, which is why people become psychologically dependent on cigarettes.

Mode of action

Nicotine stimulates acetylcholine (ACh) synapses as nicotine molecules are the same shape as acetylcholine. Acetylcholine helps synapses to modify and change, which makes synaptic transmission easier. It also stimulates the dopamine reward system. The ACh synapses are associated with thinking and learning, with greater stimulation increasing alertness.

Nicotine binds to the ACh receptors, causing the neuron to fire more frequently due to nicotine stimulation. This reaction explains why smokers often report greater feelings of alertness or quicker reaction times. Nicotine indirectly increases the neural transmission of several neurotransmitters, dopamine being one of them in the reward pathway of the brain, generating positive feelings that act as a reinforcer for continued smoking, as with other drugs such as heroin. Nicotine may also exert a sedative effect, depending on the level of the smoker's nervous system arousal and the dose of nicotine taken.

Tolerance

Nicotine is metabolised fairly quickly in the body, disappearing from the body in a few hours. Therefore some tolerance is lost overnight, when the smoker is not inhaling nicotine, and smokers often report that the first cigarettes of the day are the strongest as their tolerance is at its lowest. Tolerance progresses as the day develops, and later cigarettes have less effect.

The symptoms of withdrawal, rather than the effect of the drug itself, create a tolerance cycle as the person smokes more frequently to avoid the negative symptoms of withdrawal. While nicotine is extremely addictive, not all smokers will feel the need to increase their intake, with some maintaining a low level of nicotine use for many years, while others quickly increase.

Withdrawal

Withdrawal symptoms may begin within a few hours after the last cigarette and include irritability, sleep disturbances, headaches, difficulties in concentrating and increased appetite. Symptoms generally peak within the first few days and may subside within a few weeks, although for some people they may persist for months or longer. Craving nicotine is considered a major obstacle to overcome when stopping smoking. Experiencing an urge to have nicotine can last for up to six months, and for some the pleasure of smoking makes it a constant battle not to reach for a cigarette.

Evaluation of biological explanations

The presence of withdrawal symptoms support the biological viewpoint that the brain relies on the drug to function, as the symptoms indicate a deficit of the relevant neurotransmitter. It is possible to use brain scanning and other objective assessments such as blood tests to look at the effects of substances within the body. This provides a scientific approach to investigating the effects of substances. As the outcome of such tests can be seen, and can be replicated due to their scientific approach, the findings are considered reliable.

Many studies into the effects of drugs are undertaken on animals. For example, the Richardson and Roberts (1990) study to look at the reinforcing effect of opiates was carried out on rats. Rats have similar brain structures to humans but humans are influenced by social conditions, which may influence substance misuse, so the findings may not be applicable to humans. However, research using animals that highlight significant brain structures implicated in drug misuse are likely to be very appropriate in explaining human addiction.

Learning explanations

All of the theories from the learning approach can be used to explain why someone may start to use drugs or continue to take them. It will be helpful to familiarise yourself with these theories so that you can confidently apply them to the topic of substance misuse.

The acquisition stage of drug use explains how an individual comes to engage in the drug-taking behaviour, for example how they come to engage in heroin use, smoking or the drinking of alcohol. This occurs through the development of an association between the drug and pleasurable feeling that occurs as a result of taking the substance, which may include feelings of relaxation. This is a form of classical conditioning. Social learning theory can also explain the acquisition stage. Individuals start to smoke, drink alcohol or take heroin as a result of observing those around them engaging in such behaviours and witnessing them receiving the vicarious effect from it. This acts as vicarious reinforcement.

The maintenance stage of substance use is best explained by operant conditioning. Having a positive experience from taking a substance, for example having a buzz from heroin or feeling a sense of well-being after drinking alcohol, acts as a powerful reinforcer that makes the behaviour more likely to be repeated in the future. The punishment of withdrawal symptoms should the individual stop taking the drug will also act to maintain future repetition.

Operant conditioning

Central to the learning approach is the concept of reinforcement. Positive reinforcement explains the early stages of someone continuing to take a substance after they have tried it. It explains why individuals continue to take heroin, nicotine and alcohol.

The drugs initially create positive feelings in the person. Alcohol and heroin have relaxing benefits and can induce a sense of well-being. Heroin may also remove any feelings of pain. All of these effects can be reinforcing to the individual. They make the individual want to take the drug again in order to recreate the same effect. They learn to associate the drug with the positive feelings they experience after taking the drug.

Positive reinforcement is not always due to the consumption of the drug. Drugs, such as alcohol and nicotine, are often taken socially and reinforced by the approval of friends or peers, so continuing to drink or smoke can also be reinforced by praise from those important to us.

Operant conditioning helps to explain the maintenance of drug use. For example, the symptoms of withdrawal from heroin can be unpleasant. Heroin users, therefore, continue to use the drug to avoid the negative symptoms of withdrawal. This is an example of negative reinforcement where the drug-taking behaviour is undertaken to avoid a negative consequence (withdrawal).

Social learning theory

According to social learning theory, our observations of other people engaging in addictive behaviour can lead to the development of addiction. When we observe the behaviour and reactions of other people using drugs, we may wish to repeat what we saw, particularly if the person is considered a role model or is looked up to by the individual. It may be that the individual observes the positive experience in the other person when they use the drugs, and they therefore want to experience a similar reaction and so they use the drug.

This explanation explains smoking behaviour and alcohol use, both of which can be considered social behaviours; the drug-taking behaviour can form part of the group's culture and is, therefore, readily engaged in within social settings.

Social learning theory is particularly suited as an explanation for nicotine use, particularly as initial attempts at smoking may result in nausea and, therefore, are not initially reinforcing. For example, a person may look up to an elder sibling. If their sibling is observed smoking, the younger person may want to copy this behaviour due to their sibling being a role model.

Developmental psychology

Adolescence is a critical period in the development of smoking, and is, therefore, of concern to developmental psychologists. Peer modelling and pressure to initiate smoking behaviour is a key factor in the development of smoking and its continued use into adulthood.

As the path from initiation and experimental stages of drug misuse in teenage years through to adulthood is strong, developmental research into drug misuse has important applications in identifying at risk groups and developing health strategies and regulations to prevent drug misuse early on.

Raising the age limit to purchase nicotine and alcohol helps towards preventing teenagers being able to access these drugs, so limiting the availability within the population and, therefore, their exposure. In order for this theory to explain substance use, the person has to observe an individual undertaking the behaviour. This can occur in person, for example among friends, or can be via the media.

Many television programmes include pub scenes, for example, where everyone is shown to be having a positive and enjoyable time while drinking. This can be appealing to others who choose to copy this behaviour in order to have the same experience.

Social learning theory is less effective as an explanation of heroin use. Individuals may experiment with heroin because they see their favourite television character doing so but are less likely to be exposed to peers engaging in such behaviour, unless they are submerged in a drug-taking subculture. However, heroin is not a drug that is particularly glamourised by the media; in fact it is often portrayed with negative consequences for the user.

Classical conditioning

Classical conditioning can be helpful to explain the development of addiction and tolerance to some drugs. The central premise of classical conditioning is based on that of a system of learned association. Behaviour is repeated as a result of developing an association between a specific behaviour, such as taking heroin and the association with the pleasurable feeling for engaging in the behaviour, such as feelings of euphoria. An association between heroin and euphoria is established quickly, explaining why it has such addictive properties. Alcohol can also be explained by a learned association between drinking and its inhibitory and sedative qualities.

An individual can also develop an association between environmental cues and the behaviour, which makes it more likely they will engage in taking the drug in specific situations. For example, a person may associate eating a meal with having a drink. The meal would, therefore, be seen as a conditioned stimulus and the individual will experience cravings for a drink with a meal. Identifying these environmental cues can help an individual in treating an addiction, as they may seek to address, and, therefore, reduce the association between the environment and drug by engaging in alternative behaviours when in such environments.

Classical conditioning explains the use of heroin as well as the consumption of alcohol. The initial aversive reaction of nicotine, however, does not create an association between a cigarette and a positive reward. As a result, nicotine use is less likely to be explained via the classical conditioning approach.

Siegel et al. (1982) - Tolerance and classical conditioning

Evaluation of learning explanations

Social learning theory explains why someone might start using drugs because of external influences such as peers, family or the media. This was found in the study of Ennett, Bauman and Koch (1994) where spending time with friends who either smoke or do not smoke makes it more likely individuals will also act the same way (although non-smoking friendship groups were more likely to establish anti-smoking norms). The explanation of external influences is not considered within the biological approach. Within the learning approach external influences provide an explanation for the 'nurture' side of the nature-nurture debate.

Social learning theory highlights how family members may act as role models that can help to explain trends in alcohol use in families. However, families also share genes, and this may be a contributory factor. It is, therefore, not possible to clearly determine whether the influence in alcohol use is social or genetic.

Many drugs are known to create a response that is rewarding to the individual and can, therefore, positively reinforce their behaviour. Operant conditioning provides an explanation as to why individuals carry on taking drugs after a positive experience. Not every incident of drug taking, however, is positive.

Classical conditioning cannot explain why people start smoking, because most people report that the taste of their first cigarette was unpleasant. This should put people off but it does not, suggesting that there are additional influences other than positive reinforcement in the acquisition of an addiction to nicotine. However, it is a very good explanation for the acquisition of a heroin addiction because the first use of heroin creates feelings of pleasure.

Individual differences

There are other explanations that seek to explain why some individuals may be more likely to engage in substance-taking behaviour. These individual differences are not present in everyone, and can help to explain individual variation in drug-taking behaviour.

Personality characteristics

Sensation-seeking personality

Some individuals have a preference for engaging in risk-taking experiences. It is a personality trait and they will readily engage in sensation-seeking behaviour that creates a strong personal response. This can include undertaking extreme sports but can also contribute to drug-taking behaviour as another risky activity. Zuckerman (1979) originally identified this trait in individuals. He initially wanted to look at the reasons behind why adolescents took risks in relation to friends and sports. His study found a high correlation with this personality trait among drug users.

Personality disorder

There is a correlation between the presence of various personality disorders and drug or alcohol addiction. What is not fully clear is whether the presence of a personality disorder makes a person more vulnerable to substance use, or if the substance use contributes to the development of later personality disorders. Irrespective of the difficulties in identifying whether one contributes to the presence of the other, the presence of personality disorder and a substance use problem results in these disorders being described as co-morbid conditions. They are both present and both create difficulties for the individual.

Extraversion

Extraverted personalities are often associated with alcohol consumption and smoking, though smoking to a lesser extent. Martsh and Miller (1997) looked at extraversion as a predictor of alcohol use, and of binge drinking. They suggest regular drinkers are more extravert than light or non-drinkers, but alcoholics are more introverted than social drinkers.