SUBSTANCE USE AND ADDICTIONS Flashcards
List examples of positive reinforcement in causing drug addiction
Escapism
Get high
Like it
Stay awake
List examples of negative reinforcement in causing drug addiction
Boredom
Sleep
Reduce anxiety
Feel better
What is the ICD-10 classification of harmful substance use?
Actual damage caused to mental/physical health of user in absence of diagnosis of dependence syndrome
What is the ICD-10 diagnostic criteria of dependence syndrome?
3 or more in the past 12 months:
- Strong desire/sense of compulsion to take substance
- Difficulty controlling substance taking behaviour in
terms of onset, termination, levels of use
- Physiological withdrawal state when substance use has
stopped/reduced
- Evidence of tolerance (need to take more)
- Progressive neglect of other interests
- Persistent substance use despite clear evidence of
harmful consequences
What are the 2 types of harm caused by drug use?
Harm to users
Harm to others
What is the definition of addiction?
Compulsive drug use despite harmful consequences, characterised by an inability to stop using; failure to meet work, social or family obligations
Tolerance + withdrawal depending on drug
What is the definition of dependence?
Physical adaptation to a substance
- tolerance/withdrawal
Can be dependent and not addicted
What are some examples of behavioural addictions?
Gambling disorder
Internet gaming disorder
What does a faster effect/entry on the brain from a drug cause?
More “rush” and more addiction
Coca leaves –> Coca paste –> Cocaine –> Crack
Chewing tobacco –> Snuff –> Cigs/vaping
How does the brain change from drug use to addiction?
Pre-existing vulnerability e.g. family history, age
Drug exposure causing compensatory neuroadaptations to maintain brain function
Cycles of remission and relapse or sustained recovery
Why are younger individuals more likely to be addicted?
High neuroplasticity in younger individuals
How does alcohol work?
Enhances benzodiazepine and GABA-A receptor coupling making it more efficient. Increased inhibitory system
Alters the balance between brain’s excitatory (glutamate-NMDA receptor) and inhibitory system
What does drinking acutely cause?
Excitatory system blocked (impaired memory)
Inhibitory system boosted (anxiolysis, sedation)
What does chronic alcohol exposure cause?
Upregulation of excitatory system (more NMDA receptor)
Reduced function in inhibitory system (tolerance)
- GABA-A receptor switches subunits to be less sensitive
to alcohol
What occurs in alcohol withdrawal after chronic drinking?
Neuroadaptations meaning GABA and glutamate systems no longer in balance
Due to more NMDA receptors (upregulation) increase in Ca2+ inside cells which is toxic and causes hyperexcitability (seizures) and cell atrophy
How do we treat alcohol withdrawal?
Benzodiazepines e.g. diazepam to boost GABA function and counter increase of NMDA receptors
What is acamprosate?
Medication to help people remain abstinent - reduces NMDA function
Potentially neuroprotective
What are the models/causes of addiction?
Reward deficiency (+ve reinforcement)
Overcoming adverse state e.g. withdrawal, anxiety (-ve reinforcement)
Impulsivity/compulsivity
What is the chemical released in response to reward and where?
Dopamine
Ventral striatum
What is the dopamine pathway often referred to as?
Pleasure-reward-motivation system
What are some key modulators of the reward system?
Opioid system particularly mu opiod which mediates pleasurable effects
GABA-B
Cannabinoids
Glutamate
How do cocaine and amphetamine work?
Cocaine blocks dopamine reuptake
Amphetamine blocks dopamine reuptake and enhances release of dopamine
How do alcohol, opiates and nicotine work?
Increase dopamine firing in ventral tegmental area (VTA)
What is the relationship between availability of D2 receptors and psychostimulant effects?
Those with high D2 receptor didn’t find stimulant as enjoyable as those with less available D2 receptors
Excess dopamine can cause paranoia and anxiety
