W7 - Rob Hester 1: Addiction Flashcards
What is the largest contributor to disease burden in Australia?
Dependent Drug Use
- Alcohol and Tobacco
- Highest causes of preventable death (15,000 per year)
What are some persepctives of addiction
- Social Problem
- Brain Disease
Consequences of viewing addiction as a social problem?
- Social Stigma
- Treatment for addiction and drug dependency becomes unnecessary or ineffective
- Current government policy still emphasise personal responsibility
Viewing addiction as a brain disease? What is the field of study
- Addiciton neurobiology
- Support ‘disease principle of addiction’
- Addiction is a neurobiological disease—it is not a lifestyle choice and its about time we start treating it (as a health problem rather than a social problem)
What evidence, and implications, suggest that addiction is not a brain disease?
Evidence
Vietnam war soldiers. Only 5% of dependent users relapsed after returning to USA (though typical relapse is 75%)
Implications
- Addiction is an entrenched habit that alters the brain in the way that other learned habits do
- It is not a disease, rather it is an example of a habit formed within a particular context using the learning mechanisms in the brain
- Medicalisation is unhelpful and potentially harmful
What evidence supports drug addiction, or addiction more generally, being a brain disease that features dysfunction of self-control?
People who are drug dependent have poor self control > transitions from regular use to drug dependence and their risk for relapse
How are drugs produce addiction?
- Drugs produce euphoria by overactiving limbic centres via. release of Dopamine in NAc
- Limbic centres is tied to hippocampus, repeated pairing of drug-induced euphoria with drug-related stimuli creates association
What evidence suggest there is a biological link between drug-related craving and relapse?
- In both active and abstinent drug users. showing drug-related stimuli activates limbic regions usually associated with the effects of the drug
- Strenght of craving related in cue-related limbic activity
- Magnitude of activation predicts subsequent relapse
Suggests underlying mechanism
What is MA use associated with? What is a catch regarding this impairment?
Significant impairments in a range of cognitive domains
- Verbal Memory
- Processing Speed
- Executive Function
- Magnitutde of impairment is signficiant
Use behaviour (frequency, duration, quantity) does not predict level of impairment
- Include genetic variation in suspectibility to MA toxicity
- Impairment worse in older, men, and confounded by comorability
What is a key region responsible for emotion processing in the brain
Insula
- Critical to craving of drugs, food, etc
- Example of underlying biological/neural problem
What is the evidence for Dopamine Hypothesis in addiction
In people with low level of d2 receptors (closed star on the figure), the large drug-induced increases in DA result in optimal stimulation
- Low D2 = Vulnerability to addiction
- High D2 = Protective factor in siblins of drug dependent
Again, underlying biological processes
What is the genetic evidence for Dopamine hypothesis
Taq1A allele influences D2 density
- 2 Copies = Reduced D2 receptors
- Associated with hyodopaminergic state (low dopamine)
- Benefits from external stimulation
- Reinforcement (positive/negative) associated with dopamine stimulation is linked to drugs, giving it greater salience and increased desire to seek it
Evidence for Taq1A
- People with Taq1A gene 2-5x more likely to develop drug dependence
- Associated with poor response to treatment, with higher relapse
In inpulsive individuals, what is associated
Low D2
- Giving small amphetamine results in greater D2 release
- Impulse (Poor self-control) leads to enhanced dopaminergic stimulation
- Elevated response associated with stronger desire for drug
