4.6 - Substance use and addictions Flashcards

1
Q

What are drugs that may cause addiction?

A
  • alcohol
  • nicotine
  • cannabis
  • stimulants (amphetamine, crack cocaine, ecstasy)
  • opioids (heroin, fentanyl, DF118)
  • ketamine
  • solvents
  • GHB, GBL
  • benzodiazepines
  • psychedelics (LSD, magic mushrooms)
  • nitrous oxide
  • khat
  • ‘novel psychoactive substances’ - 950 synthetic, categories (depressant, stimulant, hallucinogenic, cannabinoid)
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2
Q

What are the three types of reasons why people take drugs?

A
  • positive reinforcement - ‘gain a positive state’
  • negative reinforcement - ‘overcome adverse state’
  • ‘normal’
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3
Q

What are examples of positive reinforcement reasons as to why people take drugs? (4)

A
  • escapism
  • get high
  • stay awake
  • like it
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4
Q

What are examples of negative reinforcement reasons as to why people take drugs? (4)

A
  • boredom
  • to get sleep
  • reduce anxiety
  • feel better
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5
Q

What are examples of ‘normal’ reasons as to why people take drugs? (5)

A
  • why not?
  • everyone does it
  • rebel
  • to fit in
  • curious
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6
Q

Why are the reasons for drug use important?

A

Can inform treatment

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7
Q

Describe the course of drug use and how it may develop into an addiction.

A
  • like, want, need
    1. experimental/’recreational’ use - causes no/limited difficulties to user (majority of population)
    2. increasingly regular use (fewer people) - dependence being developed, harmful
    3. may spiral into dependence (smaller number) - patient needs drug to function

Reversible arrow between 1 and 2

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8
Q

What does the reversible 2-way arrow between stage 1 and 2 of the course of drug use indicate?

A

Patients can revert back to previous experimental state with enough help

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9
Q

What is the ICD definition of ‘harmful substance use’ and how does this differ to hazardous use?

A
  • harmful substance use - damage to user whether that be mental or physical health, in absence of dependence syndrome
  • hazardous use means it is likely to cause harm if continued
  • moderate use –> hazardous use –> harmful use –> dependence/addiction
  • hazardous (quantity and freq high), harmful (consequences), dependence/addiction (tolerance and withdrawal)
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10
Q

What are the ICD-10 diagnostic criteria for dependence syndrome? (6)

A
  1. a strong desire or sense of compulsion to take the substance
  2. difficulties in controlling substance-taking behaviour in terms of its onset, termination, or levels of use
  3. a physiological withdrawal state when substance use has stopped or been reduced
  4. evidence of tolerance: need to take more to get same effect
  5. progressive neglect of alternative interests
  6. persisting with substance use despite clear evidence of overtly harmful consequences
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11
Q

What do we ask patients regarding difficulties in controlling substance-taking behaviour (2nd criteria)?

A
  • who has control, you or the drug/behaviour?
  • when did you last have a drink/drug?
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12
Q

What does physiological withdrawal state (3rd criteria) mean for the patient?

A

A ‘negative’ state from uncomfortable to intolerable, so user takes drug/alcohol to get relief from it/to treat it

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13
Q

Using the ICD-10 dependence syndrome criteria, when are you classed as dependent?

A

You have to meet 3 of the 6 criteria in the last 12 months

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14
Q

Which areas have the highest prevalence of problematic drug users/dependent drinking?

A

The most deprived local authorities/deprived communities have the highest prevalence of problematic drug users/dependent drinkers

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15
Q

What % of adults in need of specialist treatment for alcohol are not receiving it?

A

82%

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16
Q

How did COVID impact prevalence of alcohol and drug (opiate) dependence?

A

Increased it massively

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16
Q

What % of adults in need of specialist treatment for opiates are not receiving it?

A

46%

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17
Q

What is addiction?

A
  • compulsive drug use despite harmful consequences, characterised by an inability to stop using a drug
  • failure to meet work, social or family obligations
  • tolerance and withdrawal (depending on drug)
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18
Q

What is dependence and how is this different to addiction?

A
  • in biology/pharmacology, dependence refers to a physical adaptation to a substance
  • underpins tolerance/withdrawal e.g. opioid, benzodiazepine, alcohol
  • so you can be dependent and not addicted (does not affect functioning but requires drug use to stop withdrawal etc)
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19
Q

What are two examples of behavioural addictions?

A
  • gambling disorders - many similarities with substance dependence, reclassified as behavioural addiction from ‘impulsive control disorder’ in DSM-V/ICD-11
  • internet gaming disorder - added to ICD-11 under addictive disorders
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20
Q

Identify whether this meets the criteria for hazardous/harmful use, or addiction/dependence:
Phil → drinks 4 pints of Stella most evenings and says his drinking doesn’t cause problems

A

Hazardous use - 2.8 units (in a pint) x 4 x 7 = 78.4 units (UK recommended weekly limit = 14)

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21
Q

Identify whether this meets the criteria for hazardous/harmful use or addiction/dependence:
Jenny → drinks a bottle of wine most evenings, more at weekends. Occasionally misses work because of hangovers

A

Harmful use - since there is a physical/social/psychological impact (missing work)

22
Q

Identify whether this meets the criteria for hazardous/harmful use or addiction/dependence:
Tom → Drinks cider first thing each morning to stop himself shaking. Regards drink as a medicine, believes he wouldn’t get by without it. Doesn’t tend to get drunk

A

Dependence/addiction - tolerance and morning drinking to relieve, withdrawal

23
Q

Identify whether this person has a drug problem:
Katie → broke her ankle 6 months ago which healed well and is back to playing football. Is still taking her opioid painkillers which are on repeat prescription

A
  • likely biologically dependent as has been taking opioids for many months
  • no evidence of taking more than is prescribed (i.e. suggesting ‘abuse’) but need to ask if this is the case and why it is on repeat
  • has it just happened through error/lack of review or has she requested it?
24
Q

Identify whether this person has a drug problem:
Samson → Broke his ankle 3 months ago and says he is still in pain. Is still taking his opioid painkillers and often requests his prescription earlier

A
  • likely biologically dependent as has been taking opioids for many months
  • is taking more than prescribed so we need to ask why - for pain or to deal with withdrawal or ‘likes how it makes him feel’
  • consider harmful use - ask about any other addiction behaviours to clarify if addicted
25
Q

Identify whether this person has a drug problem:
Adam → Broke his ankle 4 months ago and is still taking his opioid painkillers, often requests his prescription earlier, is also taking up to 12 Nurofen plus tablets/day, uses alcohol and cannabis to help him sleep and has not gone back to work

A
  • likely biologically dependent as has been taking opioids for many months
  • is taking more than prescribed and buying extra as well as using other drugs
  • highly likely to be addicted
26
Q

What determines a drug’s addictive potential?

A
  • the speed a drug enters the body (faster brain entry –> more ‘rush’ and addiction)
  • its psychoactive effects
27
Q

Give three examples of how drugs can be refined for more rush and addiction.

A
  • opium –> morphine –> heroin –> snorted heroin –> injected/smoked heroin
  • coca leaves –> coca paste –> cocaine –> crack
  • chewing tobacco –> snuff –> cigarettes/vaping
28
Q

What factors are involved in drug use and addiction? Why do some people struggle with addiction while others do not? (4)

A
  • social and environmental factors (e.g. peer pressure, social drinking)
  • drug factors
  • personal factors (e.g. genetics, personality traits like impulsivity)
  • adverse childhood experiences
29
Q

Describe how addiction develops.

A
  • start with pre-existing vulnerability e.g. family history or young age
  • drug exposure –> brain has compensatory neuroadaptations to maintain brain function e.g. you may have consumed a lot of alcohol but you appear to function fine
  • you then may either have sustained recovery if you stop the drug OR cycles of remission and relapse
30
Q

What is the excitatory system in the brain?

A
  • glutamate system
  • NMDA receptor
31
Q

What is the inhibitory system in the brain?

A
  • GABA-benzodiazepine (GABA-A system)
  • GABA-A receptor
32
Q

How does acutely drinking alcohol affect the brain in terms of excitatory and inhibitory systems?

A
  • blocks excitatory system –> impaired memory (alcohol blackouts)
  • boosts inhibitory system –> anxiolysis, sedation
33
Q

How does chronic alcohol consumption affect the brain in terms of excitatory and inhibitory systems?

A
  • chronic alcohol exposure results in neuroadaptations so that GABA and glutamate remain in balance in the presence of alcohol (become adapted to the consumption of alcohol)
  • upregulation in the excitatory system
  • reduced function in the inhibitory system –> tolerance (GABA-A receptors switch subunits to make them less sensitive to alcohol)
  • this means a much larger amount of alcohol is required to reach a state of sedation
34
Q

What happens to chronic alcohol consumers in the absence of alcohol?

A
  • lack of alcohol will lead to imbalance where inhibitory system is reduced and excitatory is upregulated
  • this increased Ca2+ binding to NMDA receptor –> hyperexcitability (seizures) and cell death (atrophy)
35
Q

How do we treat the imbalance that occurs when chronic alcohol consumers are in the absence of alcohol?

A

Treat with benzodiazepines to boost GABA function

36
Q

What are the models of addiction?

A
  • reward deficiency (positive reinforcement)
  • overcoming adverse state e.g. withdrawal, anxiety (negative reinforcement)
  • impulsivity/compulsivity
37
Q

What is the role of dopamine in the brain?

A

Dopamine is a neurotransmitter that is involved in the ‘pleasure-reward-motivation’ system

38
Q

Where is the dopamine system found in the brain?

A

Ventral striatum

39
Q

What sorts of things increase dopamine levels in the brain?

A
  • natural rewards like food and sex
  • drugs of abuse
40
Q

What are key modulators of the dopamine system?

A
  • opioid system - particularly mu opioid that mediates pleasurable effects (e.g. of alcohol or endorphin rush when exercising)
  • others are GABA-B, cannabinoids, glutamate that are also targets for treatment
41
Q

In relation to dopamine, what has addiction been contextualised as?

A

As a ‘reward deficient’ state (so people take drugs to make them feel better)

42
Q

What effect does amphetamine have on dopamine?

A

Enhances dopamine release

43
Q

What effect do cocaine and amphetamine have on dopamine?

A

Blocks reuptake of dopamine

44
Q

What effect do other drugs e.g. alcohol, opiates, nicotine have on dopamine?

A

Increase dopamine neuron firing in ventral tegmental area (VTA) by reducing inhibition of release

45
Q

How can the dopamine reward pathway be assessed?

A
  • functional MRI can be used to assess function
  • records delay between the cue and target release
  • this can indirectly measure brain response during anticipation of winning money (i.e. a ‘reward’) in addiction –> monetary incentive delay task
46
Q

What is the effect of substance abuse on reward pathway?

A
  • despite using abstinent individuals, substance use will blunt activation of reward system in abstinent addicts with controls
  • less reward means that the individual will continue to take substance and experience their adverse effects
  • in abstinent addicts, those with blunted response in the brain to ‘anticipation of reward’ are more likely to relapse - consistent with ‘reward deficiency’ theories of addiction
47
Q

How may abstinence affect reward pathway?

A

With enough abstinence, the response may be restored to a level similar to that of controls

48
Q

What regions of the brain are involved in binge/intoxication, withdrawal/negative effect and preoccupation/anticipation ‘craving’?

A
  • binge/intoxication: thalamus, VGP, DGP, VTA, SMC
  • withdrawal: brainstem
  • craving: prefrontal cortex, hippocampus, BLA, insula

Ventral striatum (emotions/limbic) –> dorsal striatum (habit)

49
Q

How do habits form in addiction?

A

Craving/withdrawal –> negative emotional state and stress –> reinforcement –> habits

Ventral striatum (emotions/limbic) –> dorsal striatum (habit)

50
Q

How does reinforcement change as addiction develops?

A
  • change from positive to negative reinforcement as addiction/dependence develops
  • as neuroadaptations develop, ‘high’ becomes less and the ‘low’ becomes greater
  • people start consuming more drugs to overcome low and chase high
51
Q

How do we assess amygdala function in addiction?

A
  • fMRI of brain to look at amygdala
  • look at emotional processing of neutral and aversive images (these were not images of alcohol/drugs)
  • heightened brain response in left amygdala in abstinent polydrug addicts to aversive images but not in alcoholism
  • maybe because abstinent alcoholics have gone past the initial phase of being highly reactive
52
Q

How may staying abstinent reinforce abstinence?

A
  • greater BOLD response (inhibitory response) exhibited by abstinent patients
  • the longer one stays abstinent, the greater inhibitory response they can produce
  • this greater inhibitory response can allow them to resist drug taking and stay sober for longer
53
Q

What do altered levels of GABA-A and NMDA lead to in chronic alcoholism?

A
  • reduced sensitivity of GABA-A receptors —> tolerance (need more to get same inhibitory effect)
  • increased number of NMDA receptors —> withdrawal (causes excitability symptoms like seizures)