Biology of Addiction

Question 1

What three structures in the brain are involved in the mesolimbic dopamine system (reward pathway)?

Answer 1

Ventral Tegmental Area
Nucleus Accumbens
Projections to medial pre-frontal cortex

Question 2

Which part of the brain releases dopamine when you use an addictive substance?

Answer 2

Nucleus Accumbens

Question 3

What is unique about amphetamines as an abusive substance?

Answer 3

Amphetamine use causes 1000x the amount of dopamine release than normal.

Cocaine = 300x 
Nicotine = 200x

Question 4

What is the role of MAO?

Answer 4

Degrades neurotransmitters

Question 5

Order the 5 routes of drug administration from fastest delivery to slowest.

Answer 5

Inhalation
Injection
Snorting/snuffing
Ingestion

Question 6

What is the mechanism of THC’s action?

Answer 6

Binding to cannabinoid receptors.

Question 7

What is the mechanism of heroin action?

Answer 7

Binding to opioid receptors.

Question 8

What is the mechanism of nicotine action?

Answer 8

Binding to A4B2 nicotinic (ACh) receptors in the ventral tegmental area = increased release of DA in the n. accumbens

Question 9

What is the mechanism of caffeine action?

Answer 9

Prevents adenosine binding

Question 10

What is the mechanism of both cocaine and amphetamine action?

Answer 10

Blocks dopamine reuptake.

Question 11

What is the mechanism of action for LSD?

Answer 11

Both an agonist and antagonist.

Question 12

What has new evidence shown about the activation of certain parts of the brain in addiction?

Answer 12

On top of the reward pathway being activated, other brain systems seem to be activated as well with repeated substance use.

Question 13

What are some environmental factors that contribute to addiction?

Answer 13

Stress
Early abuse
Witnessing violence
Peers who use drugs
Availability of drugs

Question 14

Recent evidence has shown that __% of risk of addiction is genetic?

Answer 14

50%

Question 15

It was shown in experiments that the number of DA receptors a person had correlated to how much they liked or disliked a drug. True or False?

Answer 15

True.

People with a high number of dopamine receptors said the drug was unpleasant.

Question 16

There are 11 criteria for the diagnosis of substance use disorder. What are the number of criteria that need to be met to be categorized as mild, moderate, or severe?

Answer 16

Mild = 2-3
Moderate = 4-5
Severe = > 6

Question 17

Your patient has been a long time alcohol abuser. What would you see on an MRI image of the brain?

Answer 17

Brain atrophy + Increased ventricle size

Question 18

What effect does MDMA (ecstasy) have in the CNS?

Answer 18

Selectively destroys your serotonin neurons.

Question 19

What are the advantages to using partial agonists in treating addiction? (3)

Answer 19

Reduce craving for it and withdrawal
Reduce dependence potential (not a full effect)
Can act as a competitive inhibitor to the actual drug if taken

Question 20

Buprenorphine is a partial antagonist for treating what type of withdrawal?

Answer 20

Opioid withdrawal.

Hard to overdose because of ceiling effect.

Question 21

How does varenicline (chantix) work in nicotine addiction treatment?

Answer 21

It is a partial agonist of A4B2 nicotinic receptors and a competitive inhibitor of nicotine itself.