recreational drugs Flashcards
How was addiction viewed before bio explanations?
Viewed as a lack of willpower or moral weakness
What is addiction?
Changes in the brain’s reward system, making it difficult for individuals to control their impulses and cravings.
The dependence on drugs that alter the brain chemistry, leading to physical and psychological dependence
Which brain pathway is associated with addiction?
The Mesolimbic dopamine pathway also known as the reward pathway
Which NT (neurotransmitter) is associated with addiction?
Dopamine
What happens with the brain if it’s flooded with dopamine?
- Intense pleasure and reinforcement
- Dopamine receptor downregulation
- weakened prefrontal cortex control
- increased cravings and withdrawal
What is tolerance?
When a person needs increasing amounts of a substance to achieve the same effect
What three areas impact addiction?
Biological factors
Psychological factors
Social and environmental factors
What is it meant by the term recreational drugs?
Drugs that are used in the absence of medical grounds, but are taken by users for personal enjoyment
Often referred to as ‘psychoactive’ drugs as they alter brain function, which changes our mood, perception of conscious experience
E.g caffeine, nicotine, alcohol, cannabis, LSD, Cocaine, heroin
What is the reward pathway in the brain?
The brain contains reward pathways
The most important is the mesolimbic pathway
This operates on the neurotransmitter dopamine
The release of dopamine in the pathway causes us to experience pleasant and rewarding feelings
If we behave in a certain way which leads to the activation of this pathway then this encourages us to repeat the behaviour again in the future
The problem is that recreational drugs hijack this reward system. They produce pleasurable feelings without having any adaptive value
Examples of recreational drugs
Alcohol
Increasing the inhibiting effect of GABA
Blocks glutamate receptors reducing it to a fact
Affects decision-making areas and memory formation
Opiods e.g heroin and morphine
Amphetamines e.g methamphetamines
Maths taken up into the pre-synaptic neuron
Enters dopamine vesicle forcing dopamine out
Dopamine pumped to sign up to cleft
Dopamine trapped in SC so overstimulates PSN
Works directly on reward pathway
Cocaine
Stimulant effect on CNS, especially on the neurons of the mastic pathway – the brain’s main reward system
Drug achieves its effect by altering synaptic transmission involving several neuyortransmitters such as serotonin
it’s most profound impacts on the activity of dopamine
Block the uptake of dopamine by binding with dopamine transport molecules on the terminal buttons of the pre-synaptic neuron – responsible for recycling dopamine back into the neuron – the synapse is flooded with surplus quantities of dopamine, all available for binding with postsynaptic receptors
What happens when you take a drug?
Take a drug e.g heroin
In the brain - the drug increases the amount of dopamine in the reward pathways in the brain
Result - feelings of happiness
But the brain naturally reacts to the sudden increase in dopamine and so down regulates its own natural production of dopamine
What happens after you first take a drug?
The effects of the drug wear off
In the brain - the person now has less dopamine than they would have for normal brain functioning
Result - feelings of tiredness,depression and being slow
Then take more of the drug increases order to try and reproduce the high they felt when they first took it
In the brain - repeated use of the drug causes further down regulation of dopamine production.
The brain adapts to the changes imposed by the drug and so no longer operates normally without it
Result - no longer feel a high and will start taking the drug to have normal levels of brain function
How do drug users become addicted to the drug?
Then take more of the drug increases order to try and reproduce the high they felt when they first took it
In the brain - repeated use of the drug causes further down regulation of dopamine production.
The brain adapts to the changes imposed by the drug and so no longer operates normally without it
Result - no longer feel a high and will start taking the drug to have normal levels of brain function
What happens when drug users stop taking the drug?
Stop taking the drug
In brain - there is now a lack of dopamine in the brain
Result - feelings of depression and experiencing brain fog
Or they keep taking the drug increases order order to avoid withdrawal
EVALUTION for recreational drugs
Research supporting for the role of dopamine
Research using animals - deliberately damaging the mesocorticolimbic pathway in the brains of mice - neurons are unable to produce levels of dopamine normally associated with reward - mice then fail to self-administer cocaine intravenously this does not occur when the procedure is performed in other parts of the mouse brain
This supports the view that cocaines effect are due to the activity of dopamine in the brains reward system
Using animals in research
This basic transmission process in animals are similar to humans. Some differences arise because the human brain is more complex than the mouse brain - difficult to generalise the effects to humans - also isolating the effects of just one transmitter oversimplifies the process
Applications for treatments
Appplication for treatments
As knowledge of drug effects on CNS transmission grow, more treatments for addiction become available - e.g once heroin was identified as an agonist that binds to opiate receptors, other drugs were developed to reverse this
Role models - not a biological impact
