Neurobiology of Addiction

Question 1

What is the ICD-10 criteria for dependence?

Answer 1

Strong desire to take substance
Difficulties in controlling substance use
Physiological withdrawl state and tolerance
Neglect of alternative pleasures
Persistence despite evidence of harm

Question 2

What is the ICD-11 definition of gaming disorder?

Answer 2

Pattern of gaming behaviour characterised by:
Impaired control over gaming
Increasing priority given to gaming over other activities to the extent that gaming takes precedence
Continuation/escalation of gaming despite the occurrence of negative consequences

Question 3

What are the criteria under the ICD-11 for gaming disorder?

Answer 3

Behaviour pattern must be of sufficient severity to result in significant impairment in function
Should have been present for at least 12 months

Question 4

How does the brain prioritise survival?

Answer 4

Identify, select and pursue behaviours that lead to important goals = need to prioritise these goals over others

Question 5

What is incentive salience?

Answer 5

Attributing “want” to a stimulus = leads to appetitive and consummatory behaviour

Question 6

What is the pathway that is involved in wanting?

Answer 6

The mesolimbic pathway

Question 7

What is the function of the dopaminergic activity in the mesolimbic pathway?

Answer 7

Act as motivating signal
Incentivises behaviour
Involved in normal pleasurable experiences

Question 8

What effect does addiction have on dopamine receptors?

Answer 8

Functionally decreases D2 receptors

Question 9

What suggests that tolerance to reward develops in those with a gambling addiction?

Answer 9

Non-addicted individuals had increased blood flow to the striatum upon winning = gambling addicts had significantly less response

Question 10

How does tolerance to reward develop?

Answer 10

Receptors downregulate due to repeated dopamine release = increases threshold for rewards during abstinence

Question 11

What effect does tolerance to reward have?

Answer 11

Normal experiences don’t evoke adequate reward response = these changes persist despite prolonged abstinence from substance abuse

Question 12

How does positive reinforcement become negative reinforcement?

Answer 12

Initial stages of drug taking are driven by reward and eventually drug taking becomes a thirst

Question 13

What are the roles of the prefrontal cortex?

Answer 13

Helps intention guide behaviour
Modulates the effects of the reward pathway
Sets goals, focuses attention and makes sound decisions
Keeps emotions/impulses under control to achieve long term goals

Question 14

How does cortical maturation occur?

Answer 14

Back to front direction = begins in primary motor cortex and spreads anteriorly over superior and inferior frontal gyri, prefrontal cortex develops last

Question 15

When do frontal lobe areas that mediate executive functioning mature?

Answer 15

After the emotional (limbic) systems

Question 16

What are some features of the brain activity of adolescents?

Answer 16

Show strong stimulus reward and minimal judgement or impulse control

Question 17

What are the effects of dopamine release?

Answer 17

Updates information within the prefrontal cortex
Selecting new goals
Avoiding compulsive repetition of a behaviour

Question 18

What effect do addictive drugs have on the prefrontal cortex?

Answer 18

Provide a potent signal that disrupts the normal dopamine-related learning in the prefrontal cortex

Question 19

What parts of the brain are involved in forming drug habits?

Answer 19

Hippocampus and amygdala are critical in acquisition, consolidation and expression of drug stimulus learning = learned drug associations can then cue internal states of craving

Question 20

What are the roles of the orbitofrontal cortex?

Answer 20

Provides internal representations of the saliency of events and assigns values to them
Key creator of motivation to act

Question 21

How does the orbitofrontal cortex vary in addicts?

Answer 21

Show increased activation when presented with drug cues = hyperactivity correlates with self reported drug cravings following exposure to cues

Question 22

Do changes on the orbitofrontal cortex resolve after addiction is resolved?

Answer 22

No = they persist into abstinence

Question 23

How are genetics involved in addiction?

Answer 23

40-60% of risk is due to genetic factors

Low DRD2 receptor levels are at higher risk

Question 24

What may genetics affect?

Answer 24

Way we respond to drugs metabolically
How rewarding we find a drug
Behavioural traits that predispose us to take drugs

Question 25

What effect does acute stress have?

Answer 25

Triggers release of dopamine in the neural reward pathway

Question 26

What does chronic stress lead to?

Answer 26

Dampening of dopaminergic activity through downregulation of D receptors = reduces sensitivity to normal rewards

Question 27

How are stress and addiction linked?

Answer 27

Stress encourages exposure to highly rewarding behaviour = rapid increase in stress can motivate drug seeking in dependent individuals