Lecture 12 - Addiction Flashcards
What is the definition of tolerance?
- A need for increased amounts of a drug to experience the same degree of intoxification or desired effect
- A diminished effect with continued use of the same amount of a substance
What is the definition of withdrawal?
- The characteristic withdrawal symptoms of a particular substance
- The same (or similar) substance can be taken to relieve or avoid withdrawal symptoms
Aside from tolerance and withdrawal, what are the other key defining features of addiction?
The substance is taken for longer/in larger amounts than intended
Persistent desire (but unsuccessful attempts) to stop using the substance
Lots of time/effort/resources spent trying to obtain, use or recover from the substance
Social/occupational/recreational activities are stopped or reduce due to substance use
Continued use of the substance despite knowledge of the physical or psychological problems it causes
What is the ‘final common pathway’ implicated in most theories of addiction?
Increase in dopamine
What are the two key features underlying the molecular basis for tolerance?
- Receptor desensitisation (altered intracellular signalling)
- Receptor down-regulation (postsynaptic receptors are removed AND DESTROYED)
What is ‘kindling’?
A weak electrical or chemical stimulus, which initially has no overt behavioural response, results in behavioural effects when it is administered repeatedly.
Describe the effects of ‘kindling’ in terms of alcohol withdrawal
Alcohol withdrawal leads to neurochemical imbalances in the brain
During the first time withdrawing, this has no obvious behavioural effects
After repeated withdrawals, the neurochemical imbalances become exacerbated and cause seizures
What are the implications of kindling on treatment for alcohol withdrawal?
Even mild withdrawal symptoms should be treated aggressively, in order to prevent increasing severity if that individual is to go through withdrawal again
What are the 3 phases of cocaine withdrawal and in which stage are you most likely to relapse?
- Crash - decreased craving to use
- Withdrawal - high craving to use, high likelihood of relapse
- Extinction - intermittent cravings based on external cues, moderate chance of relapse
What happens to dopaminergic signalling during cocaine withdrawal?
Surviving dopmaniergic neurons in the VTA continue to fire at the same rate
However death of neurons in the VTA means there is less overall firing at the POPULATION LEVEL
Why are animal studies more useful for studying addiction than in vitro studies?
Looking at individual neurons in a petri dish does not allow you to see the changes on the population level
What is the negative reinforcement behavioural theory of addiction?
Abstinence-Withdrawal-Relapse
Drugs are taken PRE-EMPTIVELY to avoid withdrawal symptoms
(Negative feedback = you do the behaviour to avoid a negative effect)
What is the positive reinforcement behavioural theory of addiction?
Drugs are taken repeatedly to achieve the same pleasure
What is meant by ‘conditioned withdrawal’?
The withdrawal response can be evoked by environmental cues that you have come to associate with the symptoms of withdrawal
What are the implications of ‘conditioned withdrawal’ on recovery from addiction?
If someone spends time recovering in rehab and then returns home, the association between the home environment and withdrawal remains, so they become more likely to relapse upon returning home
What is the Opponent Process theory of addiction/withdrawal?
In order to achieve homeostasis, the body initiates COMPENSATORY MECHANISMS to oppose the drug action
The compensatory mechanisms for drug use are experienced as withdrawal symptoms
If you take the drug repeatedly, the magnitude of the compensatory mechanisms increase and become a conditioned response
Why might you experience withdrawal symptoms even if you take a placebo instead of the actual drug?
If you repeatedly take a drug in the same context, you become CONDITIONED to respond with compensatory mechanisms responsible for withdrawal when put in that same context
Explain how administering the same amount of a drug repeatedly can suddenly result in an overdose
Compensatory mechanisms occur due to contextual cues
If you change the context under which the drug is taken, the compensatory mechanisms will not occur
