- Both explanations can be tested with animal studies
- However, data gained from animal studies is hard to generalise to humans
- Neither explanation can give reason as to why some people are more likely to become addicted to a substance than others
- The learning approach can explain why someone first started to take drugs whereas the biological approach doesn’t and explains how the addiction occurs
- The biological approach can be scientifically tested e.g. PET scanning, whereas the learning cannot as it doesn’t explain the effects of a drug on the body
- Biological approach gives evidence for the nature argument – Klien et al 2008 said there is a genetic link to experiencing withdrawal from heroin
- Learning approach gives evidence for nurture argument – Morton et al 2001 said more involved parenting was linked to lower risk of drug use
- Biological approach cannot explain cultural differences – learning approach can suggest how our surroundings can affect the likelihood of becoming a user e.g. it is legal in Holland
- Withdrawal symptoms support the biological explanation as the brain is relying on the drug to function normally – withdrawal cannot be explained through the learning approach
- Biological explanations allow us to understand physiological dependence better than learning explanations
- Learning explanations are better at allowing us to understand physical dependence as they deal with reasons the person may find it difficult to cope without a drug
- Biological explanations can show how misuse can occur in people with no contact with other drug users as the explanation only requires exposure to the drug – learning explanation requires contact with others to act as role models
Heroin
Mode of action
- Mimics endorphin
- Body’s natural opiates
- Inhibitory neurotransmitters
- Occupy and block receptor sites for pain
- Make us feel good through the stimulation of the dopamine reward cycle
- During everyday activity, a moderate amount of endorphin is naturally produced , causing the release of dopamine and facilitating the reward systems within the brain
- If the body is under stress/pain, receptors are stimulated and the level of dopamine increases
- Lock onto brain’s receptor sites for pain
- Heroin acts like a massive release of endorphin
- Heroin floods the endorphin receptors
- Large quantities of dopamine are released – activates the reward system and produces feelings of well-being
- Heroin blocks GABA (blocks dopamine at the synapse) – dopamine floods
Short-term effects
- Rapidly produces a feeling of euphoria – 7 seconds after injection (dopamine rush)
- Analgesic effect – calm, aches and pains disappear
- Depresses most of body’s activities
- Breathing becomes slower and shallower
- Heart rate slows – stays slow so lowers blood pressure
- User feels sleepy and very relaxed
- Peripheral blood vessels dilate – feel flushed, warm, and sweaty
- When someone first takes heroin, they will feel like they want to vomit
- Heroin depresses activity of vomiting centre in brain – feeling of nausea gradually decreases as effect of heroin builds up
- Digestive system is underactive so user may become permanently constipated
- Low sex drive
Tolerance
- Develops very quickly
- Griffiths, Bigelow, & Henningfield 1980 – tolerance can increase up to tenfold in 3 to 4 months
- Regular users take a dose high enough to kill a non-user
- Body believes the normal dopamine level is higher due to chemical changes in the brain – has to have a high level of dopamine to feel normal – dose increases each time to maintain same effect
Physiological dependence
- Develops very quickly
- One fix can produce withdrawal symptoms if more is not taken in 12 hours
- Brain rapidly gets used to the influx of heroin
- Increases as tolerance does
- Established as the addict takes a fix to avoid the increasingly severe withdrawal symptoms
- Get physiological dependence get greater, psychologically, the prospect of coping without a fix feels worse
Psychological dependence
- Addict ceases to be concerned about maintaining contact with family or friends
- Focus of life becomes finding their next fix
- When not in immediate effects of a fix, the addict tends to become increasingly confused, anxious, restless, and possibly paranoid – can only be relieved with more heroin or treatment
Withdrawal
- Severity of symptoms is directly related to level of addiction
- Symptoms start 6 – 12 hours after last fix
- Failure to take a fix means symptoms will increase
- Addict becomes agitated and often very aggressive
- Symptoms peak after 26 – 72 hours
- Most symptoms are over in a week
- Becomes agitated and restless
- Alternate between feeling hot and cold
- Chicken skin (goose bumps)
- Breathing becomes short and jerky
- May then sleep for up to 12 hours but will wake to:
- Cramps
- Vomiting
- Diarrhoea
- Sweating
- Shakes
- Twitching of limbs
- Symptoms gradually subside
Alcohol
Mode of action
- Depresses activity in brain by making GABA more effective
- Slows down the speed of messages being transmitted between neurons
- Reduced effectiveness of inhibitory mechanisms that ensure we behave in a socially acceptable way – exhibitionism
- Anaesthetises nerve endings at noradrenalin synapses (trigger fight-flight mechanism) so they become less effective
- Slows reflexes because of increased GABA
- Dilates skin blood vessels
- Blocks hormone that controls urination – urination increases
Short-term effects
- Feel warm and look flushed (dilated skin blood vessels)
- Slower reactions
- Perception and speech (slurred) are affected
- Reduces people’s inhibitions (affects social control areas of the brain)
- Relaxed, confident behaviour (reduced effectiveness of inhibitory mechanisms)
- Affects motor-skills and co-ordination (depression of activity in frontal lobes)
- Dehydration (hormone controlling urination is inhibited) – as blood alcohol levels fall, urination increases – main cause of hangovers – brain can lose up to a fifth of its weight
- Heart rate slows down
- Vomiting
Tolerance
- Alcohol affects behaviour rapidly
- Short-term tolerance develops quickly – as blood alcohol levels drop, the individual feels sober before they actually are
- Alcohol consumption stimulates the body to produce an enzyme that breaks down alcohol more quickly
- In a few weeks, a drinker will need to consume around 50% more alcohol to achieve the same effect
- Behavioural tolerance is largely a result of practice – individual becomes better at coping with side-effects and appearing less drunk
Physiological dependence
- Characterised by a lack of concern for the type of alcohol consumed
- In extreme cases, alcoholics are known to drink industrial alcohol which can cause death
- Often want to start drinking early in the day as they have withdrawal symptoms – first drink alleviates these symptoms – fuels physiological dependence
- Alcoholic cannot restrict their alcohol intake as the physiological need is constant – ,many are unable to stop on a particular day until they pass out
- Lack of concern for amount of alcohol consumed
Psychological dependence
- Relief at finding a drink
- Getting access to alcohol is put above other activities e.g. eating, socialising, maintaining hygiene
- Many consume excessive amounts because of problems in their personal lives and alcoholic oblivion is welcomed as a coping strategy
- With increased use, an alcoholic becomes psychologically dependent upon alcohol – see it as a way out of their problems
Withdrawal
- Depends largely on level of use and addiction
- Habituation to the level of alcohol is extremely fast both physiologically and psychologically within a drinking bout
- Following drinking, the feeling of sobering up occurs much more quickly than the actual physiological process
- Symptoms usually appear 8 – 12 hours after the last drink – can take as long as a week
- Individual will become agitated and may have a range of other symptoms including:
- Uncontrollable shaking
- Cramp
- Nausea
- Sweating
- Irregular heartbeat
- Vivid dreaming
- Symptoms can last up to 48 hours
- For people with a heavy addiction, the effects of withdrawal are known as delirium tremens (DTs) – not uncommon to experience them whilst still drinking – habituation is happening faster than the intake of alcohol so the alcoholic experiences withdrawal even whilst drinking
- With DTs, the brain habituates to the effect of alcohol on GABA receptors and therefore has a less efficient GABA system
- Unless enough alcohol is present to depress brain activity, the fight-flight mechanism starts operating at too high of a level, producing symptoms including hallucinations, tremors, delusions, and seizures
- Untreated withdrawal is fatal in a third of cases
- Even with early treatment, about 5% of patients are likely to die