Drugs week 2

Question 1

explain the biological basis of how drugs work on the brain

Answer 1

drug is introduced = upset the balance, brain will seek to gain homeostasis through neuroadaptation.

Question 2

agonist vs antagonist neurotransmitters.

Answer 2

agonist: activate receptors (e.g. by mimicking a neurotransmitter or by increasing the existing neurotransmitter)
antagonist : block the activation of receptors

Question 3

how does the brain try and maintain homeostasis.

Answer 3

downregulation: cellular decrease in number of receptors to brain chemicals
upregulation: increase in number of receptors on surface of target cells

Question 4

What are the three biological process of tolerance

Answer 4

metabolic tolerance (pharmacokintetic) - body becomes better at breaking down the drug
alcohol:; amount of liver enzyme produced by body goes up
cellular tolerance (pharmacodynamic) : change in number of receptors

Question 5

Explain caffeine’s role on the brain

Answer 5

Works on adenosine (neurotransmitter for sleep) as an antagonist (blocks activation of receptors) also blocks GABA (circadian rhythm, at high dose)
- upregulation of A1 adenosine receptors, serotonin receptors and GABAa receptors.

Question 6

explain the role of caffeine in society

Answer 6

• psychoactive substance
  -added to 70% of non-alcoholic ‘soft drinks’
• mainly through coffee and tea.
• placebo vs caffeine = higher tolerance in caffeine.

Question 7

explain the role of nicotine on the brain

Answer 7

agonist (activates receptors) effect on acetylcholine transmitter (arousal, motivation, learning), stimulates nicotinic receptors of acetylcholine neurons.

Question 8

explain the role of alcohol on the body

Answer 8

• acts on multiple neurotransmitters
• effects : sedation, relaxation, euphoria
• crosses bbb very quickly
• non-specific: acts as depressant on all brain neurons
• disturbs neuronal membrane lipids - membrane fluidization.

Question 9

explain the specific role of alcohol on the brain

Answer 9

• inhibits glutamate (memory, emotions, sensory information, motor coordination)
  -by reducing effectiveness at NMDA glutamate receptor
  -enhances endorphin activity in the dopaminergic reward pathway, leads to disinhibition of dopamine release in the nucleus accumbens.

Question 10

explain the role of sugar and alcohol

Answer 10

• increased intake of alcohol when denied access to sugar
• access to alcohol increased sugar intake in rats
  bingeing on either sugar or alcohol fostered intake of the other
• bidirectional relationship

Question 11

explain the role of cannbis on the body

Answer 11

depends on individual and species of plant
relaxation, happiness, increased laughter, chattiness, lack of motivation nausea, anxiety, confusion
THC :psychoactive
CBD: legal in the uk

Question 12

how does cannabis work on the brain?

Answer 12

cannabinoid receptors react to THC and other cannabinoids
decreases GABA release, leads to an increase in synaptic dopamine levels.

Question 13

Explain reasons why cannbis may have become legalised.

Answer 13

1. Adverse health effects from cannabis are
   modest in relation to other legal and illicit
   drugs
2. Criminal penalties for cannabis are harmful for
   users and the community, and outweigh the
   negative consequences from use of the drug
3. If legal, cannabis can be better regulated and
   taxed
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4. Chiu et al (2022) : more liberal attitudes across most demographic groups

Question 14

explain the medical use and risk for cannabis

Answer 14

• good evidence for chronic pain, neurpathic pain and spasticity
• small risk for psychosis
• mixed evidence that could be carcinogenic
• addiction and gateway risk.

Question 15

Explain the role of synthetic cannabinoids

Answer 15

• spice
• different effects on different receptors
• Full CB1 agonist
• Lack of CBD prevents calming effects

Question 16

what are the effects of heroin and other opioids

Answer 16

addictive, relaxation, euphoria, sleepiness, happiness, less sensitive to pain and trauma, similar to endocannabinoids, heroin and morphine mimic endorphins, sit in the receptor sites of endogenous opioids. Synaptic dopaminergic neurons (involved in the reward mechanisms.

Question 17

explain the tolerance of heroin

Answer 17

quick tolerance to nausea, no tolerance ever to constipation or pinpoint pupils
cross tolerance : once tolerant you are also tolerant to morphine, codeine and methadone.

Question 18

whats the link between tolerance of heroin and overdosing?

Answer 18

• occurs when in recovery
  tolerance goes down
• individuals use habitual amount leading to overdosing.

Question 19

what are the effects of cocaine

Answer 19

• confidence, euphoria, alertness, energy and excitement

Question 20

how does cocaine work on the brain

Answer 20

• blocks the reuptake of dopamine, noradrenalin and serotonin
• acts as an agonist
• addiction due to increased dopaminergic activity in the mesocrotibcolimbic pathway

Question 21

what are the effects of amphetamines

Answer 21

high energy, excitments and chattiness
DA agonist, stimulate release of noradrenlaine

Question 22

why is MDMA not a psychostimulant

Answer 22

related as it also effects levels of dopamine and noradrneline but also hashalluconogenic effects

Question 23

what are the effects and symptoms of MDMA

Answer 23

extreme happiness, energy and feelings of love, stimulates release of noradrenaline - agonist
stimulate release of serotonin 5HT
stimulate dopamine

Question 24

what has new research suggested about therapeutic use of MDMA and other psychedelics

Answer 24

MDMA: alcohol dependence, PTSD, social anxiety in autism
Psychedelic research: Anxiety, depression, substance misuse
Licenced in 2023 in Australia MDMA = PTSD and Psilocybin for treatment resistant depression.

Question 25

How does ketamine work on the body

Answer 25

acts of CNS - local anaesthetic properties
antagonist of NMDA
reduces presynaptic releases of glutamate
can be used as antidepressant.

Question 26

explain how benzodiazepines work

Answer 26

• prescription medication with addictive properties.
• agonist for GABA, leading to muscles relaxant action
  also blocks adenosine reuptake, decreasing arousal and increasing sleepiness.

Question 27

What is addiction in simple terms?

Answer 27

chronically relapsing disorder that involves: compulsion to seek and take particular drug, loss of control in terms of limiting intake, negative emotional state when access to drug is prevented.
physical or psychological or both.

Question 28

explain what is meant by physical withdrawal syndrome

Answer 28

• due to neuroadaptation
• drug wears off- uncomfortable symptoms occur
• reverse by administering drug (negative reinforcement)

Question 29

explain the withdrawal timeline for opiates

Answer 29

10/24 hours= vomit
36/48 hours = sweating, nausea, runny nose, dilated pupils
48/72 hours = anxiety, insomnia, localized pain
72 hours/week= all symptoms gradually fade away

Question 30

explain how withdrawal work in terms of addiction

Answer 30

• shorter half life= shorter withdrawal syndrome
• start to disccoiation between physical and psychological symptoms - evidence for craving after physical symptoms have gone

Question 31

what is conditioned withdrawal

Answer 31

• pairing of CS with withdrawal leads to CR later, CS alone can induce withdrawal

Question 32

what is addiction according to the DSM-5

Answer 32

11 different criteria for substance use disorder.
- one being craving and urgers to use the substance.
- 2/3 = mild
- 4/5 = moderate
- 6 or more = severe
- does not have to include to two physiological symptoms.

Question 33

what is the ICD-11 criteria for substance misuse

Answer 33

must have two or more :
1. impaired control over substance use
2. substance use becomes an increasing priority
3. physiological features

Question 34

explain the addiction cycle

Answer 34

• preoccupation/ anticipation (cues, small dose, stressor)
• binge/intoxication (positive reinforcement)
• withdrawal (uncomfortable physiological or psychological)