Addictive Disorders Flashcards
what are the two main mechanisms underlying addiction?
tolerance
reward centres
which two ways can drug tolerance occur?
dispositional tolerance
pharmacodynamic tolerance
what is the mechanism of dispositional tolerance?
drug has a lesser effect because less of it reaches the target receptor due to changes in absorption, metabolism or excretion
what is the mechanism of pharmacodynamic tolerance?
drug has a lesser effect after it has reached the target receptor due to fewer/less sensitive receptors
explain the mechanism of withdrawal symptoms in addiction
- drug causes change in neurotransmitter release
- consistently altered amount of neurotransmitter causes compensatory change in available receptors
- ceasing drug causes the neurotransmitter level to revert to normal, whilst there is still a compensatory number of receptors
= normal neurotransmitter levels will cause either an exaggerated or reduced stimulus depending on the amount of receptors present
describe the course of the reward pathway
- stimulus causes stimulation of the ventral tegmental area (VTA)
- VTA releases dopamine
- dopaminergic neurons from VTA signal to nucleus accumbens, prefrontal cortex, hippocampus and amygdala
what neurotransmitter is released by the ventral tegmental area?
dopamine
explain the craving aspect of drug addiction
certain drugs cause an increase in dopamine release, resulting in increased firing of the reward pathway
what is the relationship between a drug’s effect and its withdrawal symptoms
a drug’s withdrawal symptoms are normally the opposite of its acute effects (eg heroin causes constipation, withdrawal causes diarrhoea)
where is the ventral tegmental area found, and why is it important?
VTA is found in the midbrain. it’s important because it forms the start of the reward pathway
which illicit drug is generally considered to be the most addictive?
crack cocaine
how can cocaine be consumed?
snorted, injected or smoked (crack)
how can amphetamine be consumed?
snorted, eaten or injected
how can heroin be consumed?
smoked, injected or snorted
name a few psychological effects of cocaine
euphoria increased confidence reduced sleep reduced appetite increased energy
why is cocaine classed as a stimulant drug? what are some of its physical effects as a result?
because it increases the body’s metabolism. it causes:
- increased body temp
- increased HR
- increased BP
- vasoconstriction
- increased resp rate
why is cocaine a risk factor for MIs and strokes?
because it’s a potent vasoconstrictor, so it increases BP which is in itself a risk factor for MI and strokes
why do chronic cocaine users present with damaged nasal septa?
because it’s a vasoconstrictor, so it stops blood flow to the septal capillaries
how long does a cocaine high normally last?
around 15 mins
how long does an amphetamine high normally last?
around 3-4 hours
how long does a metamphetamine high normally last?
around 24 hours
why is metamphetamine more addictive than amphetamine?
because its structure allows it to cross the BBB barrier more easily
what is the user population difference between crack cocaine and cocaine hydrochloride?
crack cocaine is associated with low income, crime and violence
cocaine hydrochloride is associated with success, wealth and ambition
what is the basic mechanism of action of stimulants like cocaine and amphetamines?
reduce reuptake of serotonin, dopamine and noradrenaline
