Addiction and the brain

Question 1

What is the primary role of dopamine in motor regulation?

Answer 1

Motor regulation involves the nigrostriatal pathway and the substantia nigra compacta projecting to the basal ganglia.

Question 2

Which pathway is associated with personality, perseverance, and compulsions?

Answer 2

The mesocortical pathway, where the ventral tegmental area projects to the prefrontal cortex.

Question 3

What are the functions of the mesolimbic pathway?

Answer 3

The mesolimbic pathway is involved in reward, euphoria, and intense emotions, with the ventral tegmental area projecting to the nucleus accumbens.

Question 4

Where is the ventral tegmental area (VTA) located?

Answer 4

In the midbrain (mesencephalon).

Question 5

What percentage of dopaminergic neurons are found in the VTA?

Answer 5

About 50-60% of dopaminergic neurons.

Question 6

What neurotransmitter regulates the activity of dopaminergic neurons in the VTA?

Answer 6

GABA.

Question 7

What is the role of GABAergic interneurons in the mesolimbic pathway?

Answer 7

They provide tonic inhibition of dopamine neurons.

Question 8

What effect does a reward or cue with an expected reward have on VTA dopaminergic neuron firing?

Answer 8

It leads to increased firing.

Question 9

Fill in the blank: Dopamine sensitivity is linked to personality traits like _______.

Answer 9

extraversion, sensation- and reward-seeking.

Question 10

True or False: Dopamine is targeted by most chemically addictive drugs.

Answer 10

True.

Question 11

What happens to dopamine receptors when there is an increase in dopamine levels?

Answer 11

Receptor internalization occurs, leading to fewer receptors.

Question 12

What is the main precursor for dopamine synthesis?

Answer 12

L-Dopa.

Question 13

What can too much L-Dopa cause?

Answer 13

Mania.

Question 14

What types of drugs increase dopamine release from VTA neurons?

Answer 14

Opioids, heroin, cocaine, amphetamines, cannabinoids, benzodiazepines, nicotine, alcohol.

Question 15

List the drug groups and their effects: Opiates, Stimulants, CNS depressants, Hallucinogens.

Answer 15

• Opiates: reduce pain
• Stimulants: increase alertness, intensify mood
• CNS depressants: increase drowsiness, relax
• Hallucinogens: alter perceptions, thoughts.

Question 16

What enzymes are involved in dopamine breakdown?

Answer 16

COMT and MAO.

Question 17

What is the effect of COMT variants on dopamine levels?

Answer 17

• Slow form: linked to better concentration, cognitive skills/IQ
• Fast form: linked to better stress response.

Question 18

How does nicotine affect dopamine pathways?

Answer 18

It activates mesolimbic and mesocortical dopamine pathways and projects to the TPP.

Question 19

What is the function of dopamine reuptake inhibitors (DRIs)?

Answer 19

They inhibit the dopamine transporter (DAT), resulting in elevated dopamine transmission.

Question 20

What are some clinical uses for norepinephrine dopamine reuptake inhibitors (NDRIs)?

Answer 20

Depression, ADHD, narcolepsy, Parkinson’s disease.

Question 21

Fill in the blank: Cocaine and amphetamines are examples of _______.

Answer 21

SNDRI (serotonin-norepinephrine-dopamine reuptake inhibitors).

Question 22

What are the two main types of endogenous opioid peptides involved in the reward system?

Answer 22

β-endorphin (μ receptor) and Enkephalins (δ receptor)

Both are implicated in the activation of the mesolimbic dopamine system and are associated with drug addiction.

Question 23

What system is activated by endogenous opioid peptides, leading to increased dopamine?

Answer 23

Mesolimbic dopamine system

Specifically from the ventral tegmental area to the nucleus accumbens (NAC).

Question 24

What is the significant statistic regarding fentanyl overdoses in the USA in 2016?

Answer 24

20,000 overdoses

This highlights the severity of the opioid crisis.

Question 25

What do heroin and codeine metabolize into?

Answer 25

Morphine ## Footnote This metabolic pathway is crucial for understanding opioid effects.

Question 26

What enzyme is involved in the metabolism of codeine to morphine?

Answer 26

CYP2D6 ## Footnote Genetic variations in CYP2D6 can affect the metabolism rate.

Question 27

What does a Morphine: Codeine ratio greater than 1 indicate?

Answer 27

Use of morphine or heroin ## Footnote Genetic rapid metabolisers may show a higher ratio.

Question 28

What are endorphins associated with?

Answer 28

Pain, pleasure reward, and addiction ## Footnote They play a role in the perception of exercise and reward.

Question 29

True or False: The majority of people experience a 'runner's high'.

Answer 29

False ## Footnote Most individuals report feelings of nausea or tiredness instead.

Question 30

What are the two main biological theories of exercise addiction?

Answer 30

Endorphins theory and endogenous cannabinoid theory ## Footnote These theories attempt to explain the psychological effects of exercise.

Question 31

What is the prevalence of exercise addiction?

Answer 31

5-14% ## Footnote This indicates that addiction to exercise is quite rare.

Question 32

What are the reasons the endorphin theory of exercise addiction is considered unlikely?

Answer 32

a) Endorphins do not pass the blood-brain barrier. b) Mixed results from studies with opioid antagonists. c) Modulation by exercise intensity. ## Footnote These points suggest other mechanisms may be at play.

Question 33

What psychological conditions are associated with exercise addiction?

Answer 33

OCD, anxiety, stress, substance abuse, reward sensitivity, eating/body image disorders ## Footnote These conditions may be secondary to achieving non-exercise related goals.

Question 34

What is Internet Gaming Disorder (IGD) associated with?

Answer 34

Reward deficiency, reduced impulse control mechanisms, impaired decision making, and impulsivity ## Footnote These features are common in various types of addiction.

Question 35

What neurobiological alterations are seen in IGD?

Answer 35

Activation in reward-associated brain regions and reduced activity in impulse control areas ## Footnote This reflects similarities with drug addiction.

Question 36

How does ADHD relate to Internet Gaming Disorder?

Answer 36

Less sensitivity to dopamine and impaired executive control may increase susceptibility ## Footnote Adolescents with ADHD may use cyber games to enhance focus.

Question 37

What are the offenses outlined in the Misuse of Drugs Act?

Answer 37

* Unlawfully possess a controlled drug * Possess a controlled drug with intent to supply * Unlawfully sell/give/share a controlled drug * Allow premises to be used for drug use ## Footnote These offenses highlight legal implications of drug misuse.

Question 38

What are some effects of alcohol on the brain?

Answer 38

* Increases dopamine concentration * Decreases serotonin neurotransmission * Stimulates opiate neuropeptide release * Potentiates GABA receptor function * Inhibits Glutamate receptor function ## Footnote These effects contribute to the psychoactive properties of alcohol.

Question 39

How does alcohol affect the opioid reward system?

Answer 39

Alcohol interacts with the binding properties of opioid receptors and modulates opioid peptide synthesis ## Footnote This relationship is important for understanding alcohol's addictive potential.

Question 40

What is one model proposed for alcohol reward?

Answer 40

Activation of μ-opioid receptors in the VTA and/or δ-receptors in the NAC ## Footnote Endogenous β-endorphin targets these receptors.

Question 41

What physiological response does sugar stimulate?

Answer 41

Dopamine production ## Footnote This relates to the mechanisms underlying eating disorders.

Question 42

Fill in the blank: A drop in sugar causes _______.

Answer 42

Hunger ## Footnote This reflects the body's regulatory mechanisms for energy balance.

Question 43

What happens to individuals who become resilient to insulin?

Answer 43

They won't feel full ## Footnote This can lead to issues like diabetes and overeating.