Addiction Flashcards
Define tolerance
Tolerance = loss of effect when taking the same dose
- The person may keep increasing the dose to achieve the desired effects.
- Tolerance occurs with most psychoactive substances over time.
Define dependence
Dependence = a physiological + psychological need to keep using a drug
Dependence may occue due to:
* Physiological changes (notable with alcohol, opiates, benzodiazepines)
* Psychological factors (e.g. cravings and compulsions to use the drug)
Why do withdrawal symptoms occur?
Withdrawal symptoms = occur due to physiological adaptations to the drug
E.g.:
* Benzodiazepines = stimulate GABA receptors
* GABA = an inhibitory neurotransmitter - has a relaxing effect
* Long-term use of benzodiazepines = results in the body reducing its natural production of GABA to balance the stimulating effects of the drug
* When drug is withdrawn → under-activity of GABA system → withdrawal symptoms - anxiety, irritability, tremors, insomnia, seizures
Define addiction
Drug addiction = the compulsive use of substances, often leading to harmful physical, psychological and social consequences
Which pathway in the brain is the reward pathway?
Mesolimbic pathway
* Primary neurotransmitter = dopamine
Key areas:
* Ventral tegmental area
* Nucleus accumbens
* Amygdala
* Prefrontal
Pathway of psyhcological addiction
Addictive substances or behaviours = release dopamine within the mesolimbic pathway → providing a pleasurable reward
Repeated exposure to this stimulus = reduces the number and sensitivity of the dopamine receptors in this pathway, requiring an increasingly strong stimulus (e.g., a higher dose or frequency) to produce the same reward. The response to everyday activities reduces (everyday life becomes less rewarding). As a result, the person increasingly seeks out the substance or behaviour to stimulate the reward pathway.
Which part of the brain are the cues for the addictive substance or behaviour embedded into?
Amygdala
- People, events, places or objects = can act as cues, triggering cravings.
- Stress = a common trigger → prompting the substance or behaviour as a** coping mechanism**.
What region of the brain that is responsible for executive functions (decision-making, assessing risk, controlling impulses) is also changed during addiction?
Prefrontal cortex
Examples of opioids and basic mechanism of action
Heroin, morphine, oxycodone, codeine
Stimulates opioid receptors
Examples of stimulants and basic mechanism of action
Cocaine, MDMA (ecstasy), methamphetamine
* Cocaine = blocks reuptake of dopamine by the presynaptic membrane
* MDMA = stimulates the release of serotonin + blocks its reuptake
* Meth = stimulates the release of dopamine + blocks its reuptake
Examples of depressants and basic mechanism of action
Alcohol, benzodiazepines
Stimulates gamma-aminobutyric acid (GABA) receptors
Examples of hallucinogens and basic mechanism of action
LSD, psilocybin
Stimulate serotonin receptors, particularly 5-HT2A receptors
Name a cannabinoids and basic mechanism of action
Cannabis
Stimulates cannabinoid receptors (CB1 + CB2)
Name some anticonvulsants and the basic mechanism of action
Pregabalin, gabapentin
Blocks voltage-gated calcium channels in the presynaptic membrane, reducing the release of excretory neurotransmitters
Name some nicotine products and the basic mechanism of action
Cigarettes, vapes
Stimulates nicotinic acetylcholine receptors
What is the management plan for drug and alcohol addiction?
- Detoxification (may be coordinated at home or as an inpatient)
- Medication to help maintain abstinence
- Psychological + behavioural therapies (e.g., cognitive behavioural therapy)
- Ongoing support (e.g., a recovery coordinator and support groups)
Name some medication used for opioid dependence
- Methadone (binds to opioid receptors)
- Buprenorphine (binds to opioid receptors)
- Naltrexone (helps prevent relapse)
Name some medication used for nicotine dependence (smoking)
- Nicotine replacement therapy (e.g., patches, gum or lozenges)
- Bupropion
- Varenicline
Define alcohol dependence
Alcohol dependence = involves daily alcohol consumption, strong urges and cravings for alcohol, difficulty controlling consumption, tolerance to the effects of alcohol + withdrawal symptoms when stopping.
Mechanism of action for alcohol
- Alcohol = a depressant
- Alcohol = stimulates GABA receptors (which have a relaxing effect on the brain)
- Alcohol = also **inhibits glutamate receptors (NMDA receptors) **→ causing further relaxing effct on the brain (glutamate = excitatory neurotransmitter)
Mechanism of action for alcohol dependence
- Long-term alcohol use = down-regulates the GABA system + up-regulates the glutamate system (balancing the effects of alcohol)
- The patient must continue drinking alcohol, or they will experience unpleasant, uncomfortable and potentially dangerous withdrawal symptoms.
Formula to calculate alcohol units
Volume (ml) x Alcohol Content (%) ÷ 1000 = Units of Alcohol
Tom Tip: Calculating alcohol units
Calculating alcohol units is a very common exam question. The simplest way is to multiply the volume in litres by the percentage. For example:
- For 750 mls of 12% wine: 0.75 x 12 = 9 units
- For a 25 ml shot of 40% vodka: 0.025 x 40 = 1 unit
- For 500 mls of 5.2% lager: 0.5 x 5.2 = 2.6 units
What are the recommended alcohol consumption
- Not more than 14 units per week
- Spread evenly over 3 or more days
- Not more than 5 units in a single day
Define binge drinking
Single session involving:
* Women: 6 or more units
* Men: 8 or more units
Name the complications of alcohol use during pregnancy
- Miscarriage
- Small for dates
- Preterm delivery
- Fetal alcohol syndrome
Name some complications of alcohol excess
- Alcohol-related liver disease
- Cirrhosis and its complications (e.g., oesophageal varices, ascites and hepatocellular carcinoma)
- Alcohol dependence and withdrawal
- Wernicke-Korsakoff syndrome (WKS)
- Pancreatitis
- Alcoholic cardiomyopathy
- Alcoholic myopathy - with proximal muscle wasting and weakness
- Increased risk of cardiovascular disease (e.g., stroke or myocardial infarction)
- Increased risk of cancer, particularly breast, mouth and throat cancer
What questionnaire is used to screen for harmful alcohol use?
Alcohol Use Disorders Identification Test (AUDIT)
What are the CAGE questions can be used to screen for harmful alcohol use quickly?
The CAGE questions can be used to screen for harmful alcohol use quickly:
C – CUT DOWN? Do you ever think you should cut down?
A – ANNOYED? Do you get annoyed at others commenting on your drinking?
G – GUILTY? Do you ever feel guilty about drinking?
E – EYE OPENER? Do you ever drink in the morning to help your hangover or nerves?
Name some examinations findings with excess alcohol use
- Smelling of alcohol
- Slurred speech
- Bloodshot eyes
- Dilated capillaries on the face (telangiectasia)
- Tremor
What would blood test look liek for someome using alcohol in excess?
- Raised mean corpuscular volume (MCV)
- Raised alanine transaminase (ALT) + aspartate transferase (AST)
- AST:ALT ratio **above 1.5 **particularly = suggests alcohol-related liver disease
- Raised gamma-glutamyl transferase (gamma-GT) (particularly notable with alcohol-related liver disease)
- ↑ MCV
- ↑ ALT + AST
-
AST:ALT above 1.5 → suggests alcohol-related liver disease
* ↑ GGT → alcohol-related liver disease
What is the time course for alcohol withdrawal?
- 6-12 hours: tremor, sweating, headache, craving and anxiety
- 12-24 hours: hallucinations
- 24-48 hours: seizures
- 24-72 hours: delirium tremens
What is the medical emergency associated with alcohol withdrawal?
Delirium tremens
Untreated → mortality rate is 35%
Why does delirium tremens occur?
- Long-term alcohol use = results in the GABA system becoming down-regulated → the glutamate system becomes up-regulated to balance the effects of alcohol
- Alcohol removed → the GABA system = under-functions + glutamate system over-functions
- Causes extreme excitability + excessive adrenergic (adrenaline-related) activity
How does delirium tremens present?
starts after 2d and can last up to 14d. It consists of:
Impaired mental status:
* Profound confusion
* Visual, auditory, tactile hallucinations (often insects under skin)
* Delusions
* Psychomotor agitation
Autonomic instability:
* Tachycardia + hypertension + arrhythmias
* Tachypnoea
* Hyperthermia
* Anxiety
Neurological impairment:
* Tonic-clonic seizures
* Coarse tremor
* Hyperreflexia
* Ataxia (difficulties with coordinated movements)
What tool can be used to score a patient on their withdrawal symptoms from alcohol and guide their treatment?
The CIWA-Ar (Clinical Institute Withdrawal Assessment for Alcohol, revised)
What benzodiazepine is used to combat the effects of alcohol withdrawal?
- Chlordiazepoxide (Librium)
- Diazepam = less commonly used alternative
- Orally given
Given orally as a reducing regime titrated to the required dose based on the local alcohol withdrawal protocol (e.g., 10 – 40 mg every 1 – 4 hours). The dose is reduced over 5-7 days.
Apart from benzodiazepines (chlordiazepoxide) what are the other medications used in alcohol withdrawal?
- High-dose B vitamins (Pabrinex) (IV and IM)
- Long term thiamine (oral) → prevent Wernicke-Korsakoff syndrome
What are the 3 medications given for acute alcohol withdrawal?
- Benzodiazepine (chlorodiazepoxide (Librium))
- High-dose B vitamins (Pabrinex)
- Long-term oral thiamine
What are long-term management options are available for alcohol withdrawal?
- Specialist alcohol service involvement
- Alcohol detoxification programme
- Oral thiamine to prevent Wernicke-Korsakoff syndrome
- Psychological therapy (e.g., cognitive behavioural therapy)
- Acamprosate, naltrexone or disulfiram are medications used to help maintain abstinence
- Informing the DVLA (their driving licence will be revoked until an extended period of abstinence)
What medications can be used to help maintain abstinence?
- Naltrexone
- Disulfiram
- Acamprosate
What deficiency does alcohol excess lead to?
Thiamine (vitamin B1) deficiency
- Thiamine = poorly absorbed in the presence of alcohol.
- Alcoholics = often have poor diets + get many of their calories from alcohol
What can thiamine (vitamin B1) deficiency lead to?
- Wernicke’s encephalopathy
- Korsakoff syndrome
Features of Wernicke’s encephalopathy
- Confusion
- Oculomotor disturbances (disturbances of eye movements)
- Ataxia (difficulties with coordinated movements)
Features od Korsakoff syndrome
- Wernicke’s encephalopathy → wobbly
- Korsakoff syndrome → kaught up in mind
- Memory impairment (retrograde + anterograde)
- Behavioural changes
- Wernicke’s encephalopathy → wobbly
- Korsakoff syndrome → kaught up in mind
Why is Wernicke’s encephalopathy and Korsakoff syndrome so important to prevent and involve thiamine supplementation from abstaining from alcohol?
- Wernicke’s encephalopathy = medical emergency w/ a high mortality rate
- Korsakoff syndrome = often irreversible + results in patients requiring full-time institutional care
