Biology of Reward Flashcards

1
Q

What is it important to remember about substance misuse?

A

That patients are individuals - the factors that drive patients to misuse substances are unique and individualised and should be treated as such.

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2
Q

What is better for substance misuse - treatment or prevention?

A

Prevention is better as treatment is high cost and chronic in nature

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3
Q

Why do humans like behaviours that are rewarding?

A

Pleasurable feelings from behaviour = positive reinforcement & positive valence = repetition of behaviour

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4
Q

What are the two types of rewards/highs?

A

Natural & artificial

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5
Q

What are examples of artificial highs?

A

Drugs, gambling, alcohol

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6
Q

What are examples of natural highs?

A

Food, sex, nurture & affection

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7
Q

What are the levels of the continuum of use?

A
  • Drug Use
  • Drug Misuse, Abuse
  • Problematic / Hazardous Drug Use
  • Harmful Use
  • Dependant Use
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8
Q

What type of use is this?

Psychoactive recreational substance use / experimental use

A

Drug use

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9
Q

What type of use is this?

Any unsanctioned recreational substance use

A

Drug Misuse or Drug Abuse

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10
Q

What type of use is this?

Use of a psychoactive substance at amount of rate LIKELY to lead to problems

A

Problematic / Hazardous Drug Use

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11
Q

What type of use is this?

Use of a psychoactive substance which leads to harm whether to health, psychological well being or social (dont need to be dependent)

A

Harmful Use

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12
Q

What type of use is this?

Persistent uncontrolled drug use repeatedly leading to multiple harmful consequences

A

Dependent use

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13
Q

What is the following a definition of?

State in which a person engages in compulsive behaviour, even when aware of negative consequences. Behaviour is reinforcing. Loss of control in limiting intake.

A

Addiction

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14
Q

What is the following a definition of?

Person no longer responds to a substance - higher dose is required to achieve the same effect.

A

Tolerance

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15
Q

What is another term for tolerance?

A

Hyposensitisation syndrome

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16
Q

What is the following a definition of?

Person functions normally only in the presence of a drug, There is manifested physical homeostatic disturbance when the drug is removed.

A

Dependance

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17
Q

What is delirium tremens a sign of?

A

Alcohol withdrawal

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18
Q

What social harms can arise from substance misuse?

A

Damage to property, relationships, people, destruction of families, job loss, unemployment, policing implication and healthcare provision cost

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19
Q

Which type of dependance has the highest cost to society?

A

Opiod use - IVDU

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20
Q

How does acute drug use compare to chronic drug use in terms to definition?

A

Acute drug use = Minutes-hours of use

Chronic = days-years of use

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21
Q

What are then negative risks to chronic drug use?

A

Tolerance and dependance

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22
Q

What are the risks associated with short term abstinence?

A

Withdrawal (can be v dangerous)

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23
Q

What are the risks associated with long term abstinence?

A

Cravings & relapse

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24
Q

Which part of the brain is involved in developing addiction?

A

The mesocorticolimbic system

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25
Q

What is the mesocorticolimbic system part of?

A

The coptic-basal ganglia-thalamo-cortical loop (CBGTC)

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26
Q

Which is the key structure in the brain that mediates emotional and motivational processing inc pleasure?

A

Nucleus Accumbens [NAcc]

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27
Q

Which are the two pathways involved in the msocorticolimbic circuitry?

A

Mesolimbic pathway

Mesocortico pathway

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28
Q

Where does the mesolimbic pathway run from and to?

A

From ventral tegmental area to the cingulate gyrus

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29
Q

Where does the mesocortical pathway run?

A

From ventral tegmetal area to the pre-frontal cortex

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30
Q

Which central parts of the brain are involved with reward?

A

Amygdala & Hippocampus

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31
Q

What role does the pre-frontal cortex play in addiction?

A

Impulsiveness & decision making - important for long-term addiction

32
Q

What does the nucleus accumbens release?

A

Dopamine

33
Q

In terms of dopamine - why are artificial highs more addictive than natural highs?

A

They release more powerful and reliable activation = more dopamine released more regularly

34
Q

What does blockade of dopamine release do?

A

Lessens the rewarding effects of addictive drugs

35
Q

What does activation of the mesocorticolimbic pathways result in?

A

Release of extracellular dopamine release via the nucleus accumbens

36
Q

What is a problem with long term abuse of substances in terms of natural highs?

A

P is used to euphoric artificial highs which are greater than natural highs - means they can face a lifetime of less happiness as a result

37
Q

Which substances act directly on the nucleus accumbens?

A

Opioids, cannabinoids & alcohol

38
Q

Which substances produce reward partly through non dopaminergic mechanisms?

A

Cannabinoids
Alcohol
Nicotine

39
Q

Is the nucleus accumbens only stimulated by a substance?

A

No - can also be stimulated in anticipation of the reward

40
Q

How does the brain reinforce positive valence?

A

Recognises something good has happened

Attaches positive valence to it

Strengthens the neural connections between neurons that detect stimulus and those that produce the response

41
Q

What is the name for the strengthening of neural connections between stimulus detection and response?§

A

Long term potentiation

42
Q

What describes the impact that the environment of misuse can have?

A

Associative learning

43
Q

How do Ps get addicted?

A

Initial drug = released dopamine = reinforcement of the experience,.

However - tolerance increases, so increasing amounts of drugs are needed = dependance.

Homeostatic changes & neuronal adaptations

44
Q

If a P successfully detoxes and abstains from drugs, but then relapses later - what is the risk?

A

That they will misjudge their tolerance (which has since decreased) and have higher chances of OD

45
Q

Why is there a lifelong risk of relapse?

A

Due to associative learning from synaptic plasticity

46
Q

What is psychosis?

A

A temporary detachment from reality, often with marked positive features (such as hallucinations)

47
Q

Which NT do we think is involved in the positive symptoms of psychosis / schizophrenia?

A

Dopamine

48
Q

What do anti-psychotics do?

A

Block or antagonise dopamine

49
Q

What do cocaine and amphetamine do?

A

Cause changes molecularly and cellularly that promote dysregulation (e.g. inc activity in ventral tegmental area)

AND

Cause hypofrontality (decreased blood flow to pre-frontal cortex - cant think things through as well

50
Q

How does dopamine enhance long term potentiation?

A

Modifies glutamateric transmission at D1 receptors - leading to synaptic remodelling by increased numbers of dendritic spines and branches

51
Q

What is long term potentiation?

A

Strengthening of synapses based on recent activity

52
Q

How long does long term potentiation last for?

A

Months - Years

53
Q

What does long term potentiation mean for recovery?

A

Memories in these pathways may trigger relapses years later

54
Q

How does cocaine affect D2 receptors?

A

Decreases the numbers of them (down regulates them)

55
Q

What is the consequence of down regulated D2 receptors?

A

Less D2 = adverse impacts on classic condition (learning/memory) + decreased motivation.

56
Q

What do opiates target?

A

Opiate receptors in the mesocorticolimbic circuits

57
Q

Name one area of the brain which is most adversely affected by opiods?

A

Locus coeruleus

58
Q

What does the locus coeruleus do?

A

Has noradrenergic nuclei - therefore responsible for attention, arousal & flight / fight response of ANS

59
Q

What does chronic activation of opioid receptors do?

A

Activates homeostatic mechanisms - which compensate for the functional changes caused by chronic use. This allows locus coeruleus neurons to return to their normal firing rates.

This leads to tolerance and dependence.

60
Q

What does acute opioid use do to neurons?

A

Acutely inhibits firing of the neurons in the locus coeruleus.

61
Q

What happens to the locus coeruleus in acute withdrawal?

A

There is a substantial increase in LC firing (this is what causes the physical symptoms).

This increase triggers over activation of the autonomic nervous system.

62
Q

What is the Kindling effect?

A

That withdrawal symptoms worsen with every repeated withdrawal

63
Q

What is the best way to achieve complete abstinence and return to normal living?

A

Stepwise process - includes:
- motivating P
- involving them in the treatment plan
- minimise harms done in taking subtsances
- improve physical and mental health
- Reduce criminal activity
- reduce the rates of blood-born infections
- to stop substance use, and use safer alternative in short term if necessary

Use biopsychosocial approach

64
Q

What receptors does alcohol affect?

A

GABA A (agonist)

NMDA (antagonist)

Therefore = depressive effects

Also inhibits the functioing of most voltage gated channels

64
Q

What receptors does alcohol affect?

A

GABA A (agonist)

NMDA (antagonist)

Therefore = depressive effects

Also inhibits the functioning of most voltage gated channels

65
Q

How does alcohol affect the nucleus accumbens?

A

Leads to increased dopamine release in the nucleus accumbens.

ALSO - inhibition of NMDA channels = disinhibits VTA dopaminergic neurons = increased dopamine release in the nucleus accumbens.

66
Q

What is alcohol dependance syndrome?

A

Strong desire / compulsion to drink with difficulty refraining

Withdrawal when it is stopped

Evidence of tolerance (inc or dec)

Progressive loss of pleasure in alternative interests

Persistent use despite clear evidence of harm

67
Q

What is the loss of pleasure called?

A

Anhedonia

68
Q

What are the acute effects of alcohol?

A

Agonist of GABA A
Antagonist of NMDA
Cells inhibited from firing

69
Q

What are the chronic effects of alcoho?

A

Downregulation of GABA A receptors
Upregulation of NMDA receptors
- Firing rates return to normal

70
Q

What are the chronic effects of alcoho?

A

Downregulation of GABA A receptors
Upregulation of NMDA receptors
- Firing rates return to normal

71
Q

What happens to receptors in withdrawal?

A

The balance shifts to excitation - lots of NMDA receptors allow Na to flow = lots of physical symptoms

72
Q

What are the physical symptoms of alcohol withdrawal?

A

Agitation
Tremors
Confusion
Seizures

73
Q

What are the treatment steps for alcohol dependence?

A

Assessment
Psychoeducation
Motivation for change
Safe withdrawal
Relapse prevention & treatment of underlying issues

74
Q

Which drugs can be used for withdrawal of alcohol?

A

Benzodiazepines

Oral thiamine

75
Q

Damage to which part of the brain can cause Wernicke’s?

A

Mamilliary bodies