Neurobiology of Addiction

Question 1

What is the difference between how the Moral Model and the Medical Model view addiction?

Answer 1

Moral model = people take drugs for their own benefit/ pleasure (this model leads to the criminality of drug use)

Medical model = chronic drug use alters the neurobiology of the brain => causes further impaired decision making around taking drugs

Question 2

What is meant by Novel Psychoactive Substances (NPS)?

Answer 2

These are synonymous with “legal highs”

4 main categories are:

• stimulants
• cannabinoids
• hallucinogens
• depressants

Question 3

What does the ICD-10 list as criteria for dependence?

Answer 3

• strong desire to take the substance
• difficulty controlling substance use
• psychological withdrawal state
• tolerance
• neglect of alternative pleasures
• persistent use despite evidence of harm

Question 4

What is counted as an addictive disorder in the DSM-V criteria which does NOT involve the use of drugs, alcohol or another substance?

Answer 4

Pathological gambling

Question 5

What new form of addiction will be detailed in the ICD-11?

Answer 5

Gaming disorder

• impaired control over gaming
• increased priority to gaming - i.e. it takes precedence over other activities

Question 6

What pathway in the brain is involved in addiction?

Answer 6

Mesolimbic Pathway

also knwon as the “motivational” pathway or the reward pathway

Question 7

What are the 3 main areas of the brain involved in the Mesolimbic/motivational pathway?

Answer 7

Ventral Tegmental Area (VTA) -> Nucleus Accumbens -> Prefrontal Cortex

Question 8

What neurotransmitter is released into the Mesolimbic/Motivational pathway?

Answer 8

Dopamine

Question 9

What happens when a stimulus makes MORE dopamine release into the mesolimbic/motivational pathway?

Answer 9

The desire for the stimulus is stronger

Question 10

Use of what type of drug decreases execution of rewarding behaviour due to affecting the Mesolimbic/motivational pathway?

Answer 10

Dopamine antagonist

Question 11

Why is the craving for drugs HIGHER than that of basic necessities e.g. food/water?

Answer 11

Drugs cause abnormally high release of dopamine in mesolimbic/motivational pathway

=> motivation to use drugs is higher than that of food/water

Question 12

What causes tolerance to drugs?

Answer 12

• Receptors in the Mesolimbic/motivational pathway down-regulate when the pathway is used more

=> less receptors are available to recognise dopamine

Question 13

Down-regulation of dopamine receptors still persists after prolonged abstinence to drugs. What does this result in?

Answer 13

• patients are abstinent BUT find normal daily activity unrewarding as dopamine release is not high enough
• causes a “grey period” where the pull back to drugs is HIGH as life is not motivating

Question 14

Describe the difference in positive/negative reinforcement between initial drug taking and chronic use.

Answer 14

Initial drug taking = driven by reward (positive reinforcement)

Chronic Drug use = becomes a “thirst” as patients just want to feel “normal” (Negative Reinforcement)

Question 15

What is the role of prefrontal cortex?

Answer 15

• helps our intentions to guide behaviour
• modulates the effects of the reward pathway
• sets goals/ focus attention/ make decisions
• Keep emotion and impulses under control to achieve long term goals

Question 16

When does the prefrontal cortex finish developing, and how does this affect people with addiction?

Answer 16

Still developing into early 20s

=> if addiction has been established before this point, formation of the prefrontal cortex will be disrupted

=> patients will often have a longer relationship with drugs

Question 17

What areas of the brain are involved in forming memories and habits?

Answer 17

Hippocampus
Striatum
Amygdala

Question 18

How can memory and habit affect a patient with addiction?

Answer 18

Patient develops drugs “associations”
- seeing these causes the patient to crave drug

e.g. Seeing pack of cigarettes in shop cause people to crave a cigarette

Question 19

How does the orbitofrontal cortex of the brain play a part in addiction?

Answer 19

It is responsible for the motivation to act on something (e.g. to take a drug)

Question 20

How does an underdeveloped prefrontal cortex cause addiction problems?

Answer 20

The prefrontal cortex is responsible for inhibition of the orbitofrontal cortex
=> preventing brain from acting on a motivation

=> if prefrontal cortex is underdeveloped/ has reduced functioning, its capacity to inhibit is small, and patients will be motivated to do the drug anyway

Question 21

Genetic factors highly increase the risk of drug addiction. TRUE/FALSE?

Answer 21

TRUE
Genetic factors can
- affect metabolic response to drugs
- change the reward found by taking drugs
- cause different behavioural traits that predispose taking drugs

Question 22

Give an example of a genetic problem which would affect a patients response to drugs?

Answer 22

If patient as low number of DRD2 (Dopamine) receptors

- they will already have a high tolerance and require higher doses of the drug for the same effect

Question 23

Describe the difference in how acute vs chronic stress can make patients turn to drugs.

Answer 23

Acute Stress = high dopamine release in mesolimbic/motivational pathway
=> triggers cravings (e.g. drugs)

Chronic Stress = downregulation of Dopamine receptors
=> decreased sensitivity to normal rewards
=> encourages highly rewarding behaviours (e.g. drugs)