Neurobiology of Addiction

Question 1

ICD-10 criteria of dependence?

Answer 1

a strong desire to take the substance
difficulties in controlling substance use
physiological withdrawal state
tolerance
neglect of alternative pleasures
persistence despite evidence of harm

Question 2

ICD-11 criteria for gaming disorder?

Answer 2

pattern of gaming behaviour (digital gaming or video gaming)
characterized by
- impaired control over gaming
- increasing priority given to gaming over other activities
- escalation of gaming

Question 3

CAGE model to see if people are addicted to alcohol?

Answer 3

cut down
annoyed
guilty
eye-opener

Question 4

incentive salience?

Answer 4

attributing “want” to a stimulus

Question 5

describe the reward/motivation pathway in the brain?

Answer 5

originates in VTA, projects to nucleus accumbens, then projects to prefrontal cortex
AKA mesolimbic pathway
dopamine activity
motivating signal and incentivises behaviour
cutting this pathway can block behaviour

Question 6

how do opiates, alcohol etc act on mesolimbic pathway?

Answer 6

stimulate dopamine release from nucleus accumbens

Question 7

does tolerance occur in the mesolimbic pathway with repeated stimulation?

Answer 7

studies showed that non addicts had increased blood flow to striatum upon winning
gambling addicts had significantly less response
this suggests a tolerance to reward

Question 8

what receptors are downgraded in addiction?

Answer 8

dopamine D2

Question 9

what causes tolerance?

Answer 9

repeated dopamine release, dopamine receptors down regulate
threshold for rewards during abstinence is thus increased
normal experiences don’t evoke adequate reward response
these changes persist despite prolonged abstinence from substance abuse
means relapse is very common, to get that reward feeling again

Question 10

positive vs negative reinforcement in addiction?

Answer 10

initially positive (drug taking driven by feeling of reward)
then negative (drug taking driven by negative feelings without it)

Question 11

role of pre-frontal cortex in addiction?

Answer 11

helps intention guided behaviour
modulates powerful effects of reward pathway
sets goals and focuses attention
makes sound decisions
keeps emotions and impulses under control to achieve long term goals

Question 12

pre-frontal cortex in younger ages?

Answer 12

cortical maturation progresses from back to front (primar motor cortex, over frontal gyri towards prefrontal cortex last)
frontal lobes which mediate executive functioning therefore develop last
less developed in teenagers and young people
therefore more impulsive and more likely yo take part in dangerous activity (car accidents more common in teenagers etc)

Question 13

what does dopamine release affect?

Answer 13

ability to update information within the PFC
ability to select new goals
ability to avoid compulsive repetition of a behaviour

Question 14

how do drugs affect dopamine release?

Answer 14

provide a potent signal that disrupts normal dopamine related learning in the PFC

Question 15

what areas of the brain are involved in acquisition, consolidation and expression of drug stimulus learning?

Answer 15

hippocampus
striatum
amygdala

Question 16

how is the orbitofrontal cortex involved in addiction?

Answer 16

provides internal representation of saliency of events and assigns values to them
key creator of motivation to act
increased activation when presented with drug cues in addicts

Question 17

circuits involved in drug abuse and addiction?

Answer 17

circuits involving

• inhibitory control
• motivation/control
• memory/learning
• reward/salience

Question 18

genetics in addiction?

Answer 18

most heritable complex psychiatric condition
40-60% of risk is due to genetics
- e.g lower levels of dopamine D2 receptors = higher risk
genetics can affect
- how we respond to drugs metabolically
- behaviour traits which predispose us to take drugs
- how rewarding we find drug taking

Question 19

how is stress involved in addiction?

Answer 19

acute stress = release of dopamine in neural reward pathway, this rapid increase can motivate drug seeking in dependant individuals
chronic stress = dampening of dopaminergic activity through down regulation of D receptors which reduces sensitivity to normal rewards and encourages exposure to highly rewarding behaviours