Dependence Flashcards
Define dependence.
A psychological and/or physical state resulting from repeated drug interaction.
What characterises dependence?
Compulsive drug usage on a periodic or continual basis, either to experience the psychic effects of a drug or to alleviate the discomfort of its absence.
Define psychological withdrawal.
A craving or desire to continue using the drug.
Define physical withdrawal.
The body reacts to the absence of the drug.
All drugs elicit both psychological and physical dependence. True or false?
False: all drugs induce psychological withdrawal, but only depressants induce physical withdrawal.
Why is it that only depressants induce physical withdrawal?
Depressants affect inhibitory neurotransmission, either by increasing the effects of GABA, the main inhibitory NT or by reducing the effects of excitatory NTs. To compensate for constant inhibition the body adapts to continue functioning as normal.
Give the main mechanism via which the body adapts to prolonged depressant usage.
Receptor or second messenger up-regulation
Explain how receptor/second messenger up-regulation affect neurotransmission.
Receptor up-regulation increases the generation of APs. APs increase Ca2+ influx to cells and thus increase NT release. This causes neuronal plasticity.
Explain then how addicts to depressants function as normal.
A balance is struck between the inhibition from the drug and the increased neurotransmission from adaptive mechanisms. This creates a new physiological baseline.
Why then do depressants create physical withdrawal?
Once the inhibition via the drug is removed, the adaptive mechanisms mean that increased neurotransmission is no longer balanced and above normal. Thus physical withdrawal symptoms are usually the exact opposite of the acute effects of the drug.
All drugs of abuse increase dopamine and thus reward sensation. True or false?
True, otherwise there would be no reason to do them.
Give 2 pieces of evidence that support dopamine’s involvement in reward.
- Intracranial self-stimulation experiments
- D2 antagonism prevents dopamine effects. This has shown that subjects are less likely to self-administer drugs, shown in experiments with animals.
How are opioids involved in reward?
They can decrease GABA transmission. GABA controls dopamine release, thus less GABA means more dopamine is released in the VTA.
List 6 factors that should be considered when taking drugs.
- Tolerance, i.e. dosage
- Access to the drug
- Rituality
- Speed of onset
- Duration of effects
- CNS baseline and context
There are 3 types of factor that induce drug use. What are they?
- Psychosocial
- Drug action
- Genetic
List some a) social and b) psychological factors that induce drug use.
a) Peer pressure, abuse, unemployment.
b) Existing psychological condition a sufferer wishes to alleviate, e.g. depression or anxiety.
List some factors involved in drug action that make people want to take drugs.
It stimulates the reward circuitry, after tolerance has developed and thus neuroplasticity users must continue to use drugs or they face withdrawal
List some genetic factors that induce drug usage.
Family history of addiction, gene variations in risk-taking, atypical stress responses, pharmacokinetics involved in drug metabolism
There are 2 contexts of drug usage. Define a) soft and b) hard.
a) Recreational, controlled usage. This is by choice. Often restricted to clubs or home usage, i.e. context dependent.
b) Compulsive, characterised by socioeconomic deprivation.
Drugs are often used for escape. How does this differ in a) soft and b) hard usage?
a) It is only for a while
b) Users seek oblivion
The primary reason why people begin using drugs is curiosity. True or false?
True: in the UK in 2014, 69% of people that had taken drugs said it was because they were curious.
What reinforces drug use? List 3 factors.
- Friends are all users/peer pressure
- Disrupted lifestyle e.g. abuse or poverty so addicts seek escape or recreational users seek escape from stress
- Context, e.g. when you go clubbing its well proper good if you take the droogs.
a) cocaine and b) MDMA both affect 5HT. How?
a) Cocaine blocks reuptake of 5HT
b) MDMA causes 5HT release
