Drugs

Question 1

What are drugs?

Answer 1

Tend to imitate substances already present in our nervous system particularly those that affect transmission at the synapse

Question 2

What are types of drugs?

Answer 2

Illegal
- cocaine
- opiates
- LSD

Legal
- nicotine
- alcohol
- caffeine

Question 3

How do drugs work?

Answer 3

Antagonist - block neurotransmitter

Agonist - increase effects of neurotransmitter, or mimic the neurotransmitter

Question 4

Difference between affinity and efficacy?

Answer 4

Affinity
- high affinity for a receptor if it binds to that receptor
- may not activate the receptor

Efficacy
- high efficacy if it has a tendency to activate that receptor

Question 5

How do drugs work?

Answer 5

Most stimulate the release of dopamine
- particularly in the nucleus accumbens

More dopamine = widespread reduction in activity in most of the brain (apart from nucleus accumbens)

Question 6

How do stimulants work?

Answer 6

Amphetamine
- stimulates dopamine synapses by increasing the release of dopamine from presynaptic terminal

Cocaine
- blocks the reuptake of dopamine, thus prolonging effects

Question 7

What are opiates?

Answer 7

Morphine
Heroin
- increase relaxation, decrease sensitivity to pain

Mimic endorphins
So opiates attach to specific endorphin receptors

Inhibits GABA so increases dopamine
Also blocks a hindbrain area that usually releases norepinepherine - reduction in this reduces memory storage and reduces stress

Question 8

How does marijuana work?

Answer 8

Contains cannobinoids
Binds to specific cannabinoid receptors

1. Inhibits GABA release (increase in dopamine release in nucleus accumbens) = perception of heightened awareness
2. Cannabinoid receptors abundant in hypothalamus (feeding) = increase appetite

Question 9

How does Botox work?

Answer 9

Deadly neurotoxin released by bacteria found in decaying food
Antagonist
Blocks the release of acetylcholine at neuromuscular junctions - paralysis

In small doses can be used to reduce muscle tremors and cosmetically

Question 10

How do drugs become addictive?

Answer 10

Sensitisation of the nucleus accumbens
- becomes more sensitive to substances after repeated use
- increased ability to releases dopamine in response to the substance
- reduced sensitivity to other things

Withdrawal
- cravings for the drug
- relapse causes increased sensitivity
- user learns that the drug relives distress associated with withdrawal, and so craves it more during future withdrawal

Question 11

Can we counter addiction?

Answer 11

Varenicline - treatment for smoking = partial nicotine receptor agonist

Question 12

Whats addiction?

Answer 12

Continued use of a substance when it interferes with you life

Question 13

What are the types of alcoholism?

Answer 13

Type 1
- late onset (after 25)
- gradual onset
- equal men and women
- less severe
- few relative with alcoholism

Type 2
- early onset (before 25)
- rapid onset
- more men that women
- Severe
- more relatives with alcoholism

Question 14

Is alcoholism genetic

Answer 14

Coding for an increase in risk taking behaviour
Coding for an increased stress response = more likely to relapse after quitting

Do sons of alcoholic fathers show predisposition to alcoholism
- show less than average intoxication - tolerance
- show greater decrease of stress when drinking
- slightly smaller amygdala

Question 15

Whats depression?

Answer 15

Feelings of extreme sadness and helplessness
Severe enough to interfere with daily life, and can last for works or months rather than days

Twice as common in women than men

Question 16

What causes depression?

Answer 16

Moderate degree of heritability to depression

More common among relatives of women with early onset depression

Low serotonin associated with aggression and depression

Question 17

What’s bipolar disorder?

Answer 17

Varying between mania and depression

• Increased metabolism during manic phases
• Possible genetic component - more common in monozygotic twins, but this seems to increase risk rather than cause
• treated with lithium salts

Question 18

What’s SAD?

Answer 18

Seasonal affective disorder

Depression associated with one season
Less serve than major depression
Light treatment as therapy

Question 19

Whats schizophrenia?

Answer 19

Positive symptoms - additions
- psychotic - delusions and hallucinations
- disorganised - odd emotional displays and though disorder

Negative symptoms - absences
- poor social interaction
- poor speech
- absent facial expression

Not all patients exhibit symptoms
Difficult to diagnose, often confused with other conditions

Question 20

How does schizophrenia develop?

Answer 20

Abnormalities in the development of the NS before birth and in the newborn

Infections, poor nutrition, complicated delivery

Question 21

What are some brain abnormalities in schizophrenia?

Answer 21

Ventricles (fluid filled spaces in the brain) larger, so less space for brain cells

Prefrontal cortex damage (working memory impaired)

Cell bodies are smaller in the hippocampus and prefrontal cortex

Less lateralisation than most people

Question 22

What happens at the synapses for people with schizophrenia?

Answer 22

Excess activity of dopamine synapses
- They have twice as many dopamine receptors than other people - but normal levels found

Deficient activity at glutamate synapses
- dopamine inhibits glutamate release, and glutamate activates neurons that inhibits dopamine