Drugs And Addiction

Question 1

What are drugs?

Answer 1

Imitate substances already present in our nervous system, particularly those that affect transmission at the synapse

• drugs= mainly from plants
• plant produces chemical to attract insects, to stop being eaten etc
• nervous system of many animals = similar

Question 2

How do drugs work?

Answer 2

Can affect transmission at synapse in 2 way:

1. Antagonist — blocks NT
2. Agonist— increase effect of NT/ mimics NT

Question 3

How to drugs work? (Receptors)

Answer 3

Drunk has high AFFINITY for receptor, if it BINDS to that receptor

Drug has high EFFICACY if it has tendency to ACTIVATE that receptor

Question 4

How to drugs work? Brain

Answer 4

Drugs stimulate release of dopamine — in nucleus accumbens

Drug» bursts of dopamine» inhibits GABA» increases activity in nucleus accumbens

Question 5

What is the nucleus accumbens?

Answer 5

Small subcritical area rich in dopamine receptors

Question 6

Drug stimulants: agonists

Answer 6

Amphetamine (speed)
- stimulates dopamine synpases by increasing release of dopamine from presynaptic terminal

Cocaine
- blocks reputable of dopamine, prolonging effects

Question 7

What does more dopamine result in?

Answer 7

Widespread reduction in activity in most f brain (apart from nucleus accumbens)

Question 8

How do drugs work? Opiates:

Answer 8

Morphine + Heroin
- both increase relaxation, decrease sensitivity to pain
- mimics endorphins (naturally occurring chemical in brain)
- opiates attach to specific endorphin receptors

1. Inhibit GABA - increase dopamine
2. Also blocks hindbrain area that usually releases norepinephrine

Question 9

What does reduction in norepinephrine result in?

Answer 9

Reduces memeory storage +reduces stress

Question 10

How does marijuana work?

Answer 10

• Contains cannabinoids
• bind to specific cannabinoid receptors (widespread in brain)

1. Inhibit GABA release (increase dopamine release in nucleus accumbens) = perception of high extended awareness
2. Cannabinoid receptors abundant in hypothalamus (feeding)= increased appetite

Question 11

How do drugs work? Botox

Answer 11

• deadly nerutoxin released by bacteria found in decaying food
• ANTAGONIST
• Blocks release of acetylcholine at neuromuscular junctions - paralysis
• in small doses can be used to reduce muscle tremors and cosmetically

Question 12

How do drugs relate to addiction?

Answer 12

Many addictive substances increase activity at dopamine synapses
Particularly in nucleus accumbens

Question 13

Different between wanting and liking

Answer 13

-Drugs increase NEED for substance even if experience = not pleasant

• Mice with increased dopamine production showed no more pleasure in food, but made more efforts to get it
• Mice with decreased dopamine production made less effort to get food, but ate just as much

Question 14

Drug addiction: Sensitisation of Nucleus Accumbens

Answer 14

• becomes more sensory to substance after repeated use
• increased ability to release dopamine in response to substance
• reduced sensitive to other things

Question 15

Drug addiction: Withdrawal

Answer 15

• craving for drug
• relapse causes increased sensitivity
• user learns that drug relieves distress associates with withdrawal, and so craves it more during future withdrawal

Question 16

Can we counter addiction?

Answer 16

Treatment from smocking:

Varenicline = partial nicotine receptor agonist

Varenicline stimulate + binds&raquo_space; nicotine, timulattes nictoine rectors= increased dopamine

Question 17

What considers something to be addition?

Answer 17

Continues use of substance that interfered with you life

Question 18

Alcohol and areas of brain:

Answer 18

Alcohol acts on many brain areas— mainly inhibitory effects

Question 19

2 types of alcoholism:

Answer 19

1. Late onset, gradual onset, equal men and women, less severe, few relatives with alcoholism
2. Early onset, rapid onset, more men than women, severe, more relatives with alcoholism

Question 20

Genes and alcoholism

Answer 20

Genes may influence alcoholism in many ways

1. Coding for increase in risk taking behaviour
2. Coding for increased stress responce= more likely to relapse after quitting

Question 21

Do sons of alcoholic fathers show predispositions to alcoholism?

Answer 21

1. Show tolerance to alcohol
2. Greater decrease of stress when drinking
3. Smaller amygdala (increases risk taking).

Question 22

Depression, what causes it?

Answer 22

Clinical depression:
- feelings of extreme sadness
- severe enough to interfere with daily life
- twice as commen in women

Causes:
- degree os heritability to depression, but not specific to depression (relatives likely to suffer from bulimia, anxiety, substance abuse)
- more common among relatives of women with early onset depression

• suggested that postnatal depression runs in families

Question 23

Depression and Seratonin

Answer 23

Low seratonin associated with aggression and depression

So genes controlling seratonin have been implicated
- gene controlling serotonin transporter protein
-this protein control ability of axon to re absorb serotonin

Question 24

Genes controlling serotonin: short and long types

Answer 24

This gene affects how people cope with life experiences

Short and long types:

• 2 short forms of gene = more likely to have depression in responce to stressful stimuli

Question 25

Bipolar Disorder

Answer 25

Unipolar disorder: varying between normality + depression Bipolar disorder: varying between mania + depression

Question 26

What is mania ?

Answer 26

Restless activity, excitement, confidence, rambling speech

Question 27

What happen with bipolar?

Answer 27

Increased metabolism during manic phases Possible genetic component— more common in monozygotic twins Treated with lithium salts— bocks synthesis of acid associated with brain inflammation

Question 28

What is Seasonal Affective Disorder (SAD) ?

Answer 28

- depression associated with one season (winter) - common near poles were nights are long - less severe than major depression - light therapy as treatment (affects biological clock)

Question 29

Schizophrenia

Answer 29

Split mind. Not related to dissociative identity disorder. Split refers to diviso between emotional and intellectual experiences and behaviour Some patients show innaprotirte emoonal expression that seeks detached from current circumstances Symptoms: hallucinations, thought disorder, movement disorder, psychotic, disorganised, poor social interactions, poor speech Difficult to diagnose- often confused with other conditions Difficult to pinpoint specific brain area More common in men Earlier onset on men

Question 30

Schizophrenia- is there one gene for it?

Answer 30

May not be one gene,instead combination of genes interacting with environment

Question 31

How does schizophrenia develop?

Answer 31

Neurodevelopmental hypothesis = abnormalities in development of nervous system before birth and in newborn 1. Infections, poor nutrition, complicated delivery —- only increases Schizophrenia chance slightly 2. Some slight brain abnormalities in patients, suggesting subtle changes during development

Question 32

Brain abnormalities in schizophrenia

Answer 32

1. Ventricles larger— less space for brain cells 2. Prefrontal cortex damaged (work in memeory impaired) 3. Cell bodies smaller in hippocampus and prefrontal cortex 4. Less ,arterialisation than most ppl- more likely to be left handed

Question 33

Schizophrenia: what is happening at the synapse?

Answer 33

Abused drugs associated with excess of dopamine— can cause psychosis Dopamine hypothesis of schizophrenia = excess activity of dopamine synapses Schizophrenia patients have 2x as may dopamine receptors that others Associated with lower than normal release of glutamate + fewer re perons in prefrontal cortex Glutumate hypothesis of schizophrenia = deficient activity at glutamate synapses Dopamine inhibits glutamate release and glutamate activates neurons that inhibit dopamine