Neurobiology of addiction (pie)

Question 1

What is the ICD-10 criteria for substance dependence?

Answer 1

• A strong desire to take the substance
• Difficulties in controlling substance use
• A physiological withdrawal state
• Tolerance
• Neglect of alternative pleasures
• Persistence despite evidence of harm

Question 2

What is the substance abuse (alcohol or drugs) screening tool used to assess if it exists ?

Answer 2

CAGE:

1. 1. Have you ever felt you ought to cut down on your drinking or drug use?
2. Have people annoyed you by criticizing your drinking or drug use?
3. Have you felt bad or guilty about your drinking or drug use?
4. Have you ever had a drink or used drugs first thing in the morning to steady your nerves or to get rid of a hangover (eye-opener)

CAGE questions are scored 0 for “no” and 1 for “yes” answers. Score of equal to or > 2 is clinically significant

Question 3

What pathway is involved primarily in reward?

Answer 3

• Dopaminergic pathway:
• MESOLIMBIC/CORTICAL - motivation and reward systems

Ventral tegmental area = origin of the dopaminergic cell bodies in this pathway

Question 4

What are some examples of natural reqard stimulants elevating dopamine levels through the mesolimbic pathway ?

Answer 4

Food and sex

Question 5

What are some examples of unnatural stimulants causing increased dopamine levels ?

Answer 5

• Amphetamine
• Cocaine
• Nicotine
• Morphine

Question 6

What is seen in gambling addicts on winning compared to someone who wins but is not a gambling addict ?

Answer 6

The striatum is composed of three nuclei: caudate, putamen, and ventral striatum. The latter contains the nucleus accumbens (NAcc)

• Non- addicted controls had increased blood flow to the striatum upon winning
• Gambling addicts had significantly less response
• This suggests a tolerance to reward develops

Question 7

What happens to the number of dopamine D2 receptors in addiction ?

Answer 7

• They decrease (tolerance develops)
• Due to repeated dopamine release, dopamine receptors down regulate.

Question 8

What are the roles of the pre-frontal cortex

Answer 8

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

Question 9

How is memory and habits of drug taking formed ?

Answer 9

• The hippocampal, striatum and amygdala critical in acquisition, consolidation and expression of drug stimulus learning.
• Striatum – habit learning
• Hippocampus – declarative learning
• Learned drug associations can then cue internal states of craving.

Question 10

What is seen on brain imaging in addicts when presented with drug cues ?

Answer 10

increased activation of OFC (orbito-frontal cortex)

Question 11

What is the most heritable complex psychiatric condition?

Answer 11

• Substance/ drug abuse
• 40-60% of the risk is due to genetic factors

Question 12

How can stress trigger drug seeking in dependent individuals ?

Answer 12

• Acute stress triggers release of dopamine in the neural reward pathway.
• Rapid increase can motivate drug seeking in dependent individuals.