1b Substance Use and Addiction Flashcards
What is meant by positive reinforcement?
Taking a substance to gain a positive state
What are some examples of reasons to take substances fot positive reinforcement?
Escapism
Get high
Like it
Stay Awake
What are some examples of reasons to take substances for negative reinforcement?
Boredrom
To get to sleep
Feel Better
Reduce Anxiety
What is negative reinforcement?
Taking substances in order to overcome an adverse state
Describe the course of alcohol/drug use which leads to addiction
- Experimental / recreational use which causes limited difficulties - “LIKE”
- Increasingly regular use - “WANT”
- Leads to harmful use as there is a shift in motivational desire
- Finally = spiralling dependance on the drug = “NEED”
What is the definition of a harmful substance?
A substance which when using it, places the mental and physical health of the user in danger
Hazardous = likely to cause harm if use continues at this level
What are the key diagnostic criteria of Dependance Syndrome?
- Strong desire or sense of compulsion to take the substance
- Difficulty controlling the substance in terms of termination of use - think who has control, you or the drug
- A physiological withdrawal state when the drug is stopped
- Tolerance = need to take more to get the same effect
- Neglect of alternative interests
- Persisting with substance despite clear evidence of harmful consequences
What is the definition of Addiction?
Compulsive drug use despite harmful consequences, characterised by an inability to stop using the drug; failure to meet work, social and family obligation and depending on the drug, tolerance and withdrawal
What is the biological definition of dependance?
Refers to a physical adaptation to a substance = Patients can be depedant but not addicted
What are behavioural addictions?
Gambling disorder = similarities in neurobiology and treatment approaches therefore reclassified
How does entry of the drug impact addiction?
faster brain entry = more “rush” and more addiction
Describe the path from use to addiction?
- Pre existing vulnerability - family history and age play large roles
- Drug exposure = compensatory neuroadaptations to maintain brain functions
- Leads to cycles of remission and relapse, or sometimes recovery which can be sustained
What happens once someone is tolerant to a drug?
Once they become tolerant, they then begin to experience withdrawal once the drug is not there
How does alcohol affect the brain?
Alters the balance between the brains inhibitory and excitatory systems
What is excitatory system of the brain?
Glutamate system
Which receptor does the glutamate system work on?
NMDA receptor
What is the inhibitory system of the brain?
GABA-A system
What are two common reasons to drink alcohol?
To get to sleep
To reduce anxiety
Describe the effects of acute alcohol drinking on the excitatory system?
Blocks the excitatory system = results in impaired memory (leading to blackouts)
How does memory get impaired with drinking alcohol?
Changes to the NMDA receptor result in memory loss
How does the inhibitory system get affected when acutely drinking alcohol?
Boosts the inhibitory system
- Sedation
- Anxiolysis
What does chronic alcohol exposure lead to?
Results in neuroadaptations so GABA and glutamate remain in balance in the presence of alcohol
What happens to the excitatory and inhibitory systems in chronic alcohol use?
Upregulation of the excitatory system and reduced function in the inhibitory system = tolerance
How does the GABA-A receptor change in chronic alcohol drinking?
Switch in sub-units to make it less sensitive to alcohol
Describe the withdrawal state of alcohol and what it can lead to
When the alcohol is taken away - there is still the large up-regulation of the excitatory system
This imbalance is toxic and can lead to hyperexcitability (seizures) and cell death (atrophy)
How does the NMDA receptor change in the state of withdrawal?
Increase in Ca2+
How is alcohol withdrawal treated?
Treat with benzodiazepines to boost GABA function to restore the balance and counteract the glutaminergic hyperactivity
What is the medication which reduces NMDA function?
Acamprosate
What do natural rewards (food, sex) do?
They increase the levels of dopamine in a part of the brain called the ventral striatum
What is the dopamine pathway referred to as?
Pleasure-rewards-motivation system
What is a key regulator of the dopamine system?
Opioid system - Mu opioid which mediates pleasureable effects - endorphin rush
What is the reward-deficient state?
Addiction
How do cocaine and amphetamines interact with the dopamine system?
They block the reuptake of dopamine into the pre-synpatic neurone, meaning there is a lot more dopamine available in the synapse
How does amphetamine work? (2)
Amphetamine enhances the release of Dopamine, as well as blocking the reuptake
How do alcohol and nicotine affect the dopamine pathway?
They increase the dopamine neurone firing in the VTA (ventral tegmental area)
What is the relationship between “liking” psychostimulants and the levels of V2 receptors in the brain?
Pleasurable outcome = have fewer dopamine receptors - this might be due to the fact they started with less
Non-pleasurable outcome = More dopamine = too much can lead to symptoms like schizophrenia and hallucinations and other negative effects - started with enough therefore too much is not enjoyable
How can the function of the reward pathway be assessed?
fMRI
What region of the brain is involved in the withdrawal / negative effect?
Amygdala and brainstem
What happens to the level of high as dependance and addiction develops?
The level of high decreases as the allostatic set point is lower than the homeostatic one, therefore the “high” felt is significantly less
Describe the change from positive to negative reinforcement as addiction develops?
Positive reinforcement drops, and and negative increases, with primary motivation being negative reinforcement
Describe the “stress” system?
The ‘stress’ system: increased activity in many including kappa opioid (dynorphin), noradrenaline (arousal system) CRF (stress) etc
Dysregulation in which key brain area is key for negative states during addiction?
Amygdala
Describe the changes in neurobiology when drug addiction changes from habits to compulsion?
Involves transition from Prefrontal to striatal control over drug taking
And, ventral (limbic or emotional) to dorsal (habit) striatum
The prefrontal “top-down” control is diminished with greater striatal reward drive
What is Naltrexone?
An opioid antagonist - used to block heroin use in opioid addicts and modulate the rewards system in alocholism
What is meant by harmful use?
A pattern of psychoactive substance use that is causing damage to health (physical or mental)
What is new that is included in the ICD 11?
Harm to the health of others - any form of physical hard including trauma or mental disorder
What are the three categories in the new ICD11 classification?
- Impaired control over substance use
- Increasing precedence of substance use over other aspects of life
3, Physiological features indicative of neuroadaption to the substance
What are the DSM5 Classification differences?
Opioid Use Disorder
Alcohol Use Disorder
Which conditions are important to ask about in a past medical history when doing a history taking in addiction?
Cirrhosis (Alcohol)
Endocarditis (IV)
Abscesses (IV)
BBV: Hepatitis B/C & HIV (IV)
(ask about vaccinations)
What is the CAGE screening?
Have you ever felt you needed to Cut down on your drinking?
Have people Annoyed you by criticizing your drinking?
Have you ever felt Guilty about drinking?
Have you ever felt you needed a drink first thing in the morning (Eye-opener)
Which patient population is most likely to develop an alcohol problem?
Younger men
After what time frame is the maximum alcohol concentration reached?
Alcohol is well absorbed from the mouth, stomach and small bowel and maximum blood concentration is reached within 60 minutes of ingestion.
What property of alcohol makes it well distributed in the body?
It is hydrophilic and therefore widely distributed in all bodily tissues
What does alcohol do to cause anxiolysis?
Alcohol enhances neurotransmission at GABA-A receptors
What part of the brain is responsible for the reward pathway after drinking alcohol?
It also stimulates dopamine release in the mesolimbic system
Describe the metabolism of alcohol?
Oxidised by alcohol dehydrogenase to acetaldehyde
Acetaldehyde is then oxidised by ACETALDEHYDE DEHYDROGENASE to carbon dioxide and water
What is targeted commonly in drugs to treat alcohol addiction / dependance?
Drugs to stop alcohol dehydrogenase
What clinical features are looked on examination for when making an alcohol assessment?
It also stimulates dopamine release in the mesolimbic system
What are the neurological signs which might be found in patients with alcohol problems?
Consider Wernicke’s encephalopathy and Korsakoff’s syndrome
What are the symptoms of Wernicke’s encephalopathy?
Ataxia, confusion and opthalmoplegia
What is given to patients with Wernicke’s encephalopathy?
Intramuscular, and then oral thiamine in order to reverse the effects seen in wernicke’s encepthalopathy
what happens if thiamine is given to patients with Korsakoff’s sign?
Nothing - damage is irreversible at this point
What must you do if a patient is CAGE positive?
Do a substance misuse history
Which is worse, alcohol or opiate withdrawal?
Alcohol - worsening pattern or symptoms which can lead to death
hallucinations and delirium tremors
What is the difference between Opiates and Opioids?
OPIATES - refer to naturalopioidssuch as morphineandcodeine and heroin to some extent
OPIOIDS - refer to all natural, semisyntheticandsyntheticopioids
What do Opioids do?
Relieve pain - analgesic effect
Create a sense of Euphoria
What might patients who are going through a heroin withdrawal experience?
Diarrhoea
What are the three opioid receptors called?
mu, delta, kappa
What are examples of opioid agonists?
Heroin, methadone, fentanyl, codeine
What is buprenorphine used to do?
As a substitute for heroin
What might you see on examination in a patient for opiate assessment?
Collapsed veins / track marks
Endocarditis
Skin abscesses
Hepatitis / HIV
Pneumonia
What assessment is done to measure opiate withdrawal?
COWS - Clinical Opiate Withdrawal Scale
What medication is given to people who have had a heroin overdose?
Naloxone (Narcan) - inject into upper arm / thigh , if no response in 3 minutes then repeat
provide airway support, recovery position
How does Disulfiram work as an anti-alcohol medication?
Works by blocking the breakdown of alcohol in the body. This leads to buildup of a toxic alcohol-related compound that can cause people who drink alcohol while taking this medication to become very sick. This reaction helps encourage people to avoid alcohol while taking the medication.
Which antibiotic also inhibits acetaldehyde dehydrogenase?
Metronidazole
What treatment is given to promote Opioid Abstinence?
Methadone
Buprenorphine
Give them as a substitute for the opioid in a controlled manner, and in such a way that hey can slowly reduce their useage
What is a medical emergency which can occur due to alcohol withdrawal?
Delirium tremens / seizures
What medication is used for acute alcohol intoxification?
Chlordiazepoxide (Librium) is the most
commonly used medication for acute alcohol
detoxification.
Which medication is used in both alcohol and opioid abstinence?
Naltrexone is used in both alcohol and opioid abstinence.
