Narcolepsy Flashcards

1
Q

At what point in someone’s life does narcolepsy begin?

A

Usually begins in adolescence or early adulthood

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2
Q

What does narcolepsy mean?

A

The experience of sudden and uncontrollable attacks of sleep at irregular and unexpected times

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3
Q

What is associated with narcolepsy?

A

Cataplexy

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4
Q

What is cataplexy?

A

The loss of muscular control

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5
Q

What triggers episodes of narcolepsy?

A

Emotional arousal

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6
Q

What percentage of narcoleptics have cataplexy?

A

75%

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7
Q

Name 3 other symptoms of narcolepsy

A

1) Hallucination
2) Sleep paralysis
3) Frequent waking up

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8
Q

Name the 3 explanations of narcolepsy

A

1) REM
2) Immune system
3) Hypocretin

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9
Q

When was the REM explanation of narcolepsy created?

A

In the 1960s

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10
Q

Outline the REM explanation of narcolepsy

A

It is a result of the malfunction in the symptoms that maintain REM sleep

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11
Q

What evidence is there for the REM explanation of narcolepsy?

A

One of the symptoms of narcolepsy is cataplexy which is similar to what happens in REM sleep and during the day, sufferers often experience intrusions of REM-type sleep or hallucinations and at night, experience abnormal REM

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12
Q

Name and explain the 2 studies supporting the REM explanation of narcolepsy

A

1) Vogel (1960) - found REM occurred at the onset of sleep in narcoleptics which explains some symptoms like loss of muscle tone (found in REM) and hallucinations (REM-type sleep)
2) Siegel (1999) - recordings of neural activity in the brainstem of narcoleptic dogs - showed cataplexy co-occurred with brain cell activity that usually only occurs in REM - however general support not convincing

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13
Q

When was the immune system explanation of narcolepsy put forward?

A

In the 1980s

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14
Q

Outline the immune system explanation of narcolepsy

A

Narcolepsy is linked to a mutation of the immune system

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15
Q

Name the 3 research studies associated with the immune system explanation of narcolepsy

A

1) Honda (1983)
2) Stanford Medical Centre (2012)
3) Mignot (1997)

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16
Q

Outline Honda (1983)

A

Found increased frequency 1 type of human leukocyte antigen HLA which coordinate the immune response and found on the surface of white blood cells

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17
Q

Outline Stanford Medical Centre (2012)

A

Found more than 90% of narcoleptics with cataplexy found HLA varient - but not all so cannot be the only factor and it is not clear how HLA may lead to narcolepsy

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18
Q

Outline Mignot (1997)

A

The same HLA varient is reasonably common in the general population - so HLA varient cannot be the only cause

19
Q

When was the hypocretin explanation of narcolepsy put forward?

A

In the 1990s

20
Q

What is the role of hypocretin?

A

Maintaining wakefulness

21
Q

What research study supports the role of hypocretin?

A

Sakurai (2007) - found hypocretin regulates sleep and wakefulness through interactions with systems which regulate emotion and homeostasis in the hypothalamus

22
Q

How many hypocretin-producing cells are normally present in individuals?

A

10,000-20,000

23
Q

What is a significant piece of evidence which supports the idea of hypocretin associated with narcolepsy?

A

In narcoleptics, a large number of hypocretin-producing cells are missing resulting in low levels of hypocretin

24
Q

Name and explain 2 studies supporting the hypocretin explanation of narcolepsy

A

1) Lin (1999) - found narcoleptic dogs had mutation in gene on chromosome 12 which disrupted the way hypocretin is produced - findings confirmed in human studies
2) Nishino (2000) - found human narcoleptics had lower levels of hypocretin than normal in their cerebrospinal fluid

25
Q

It is likely that genetics cause narcolepsy?

A

No as it is rarely due to a gene - Mignot (1998) in cases where one twin has disorder, not found in the other twin

26
Q

What 5 things are likely to actually cause narcolepsy?

A

1) Brain injury
2) Infection
3) Diet
4) Stress
5) An autoimmune attack

27
Q

Outline Mignot (1998)

A

In cases where one twin has disorder, not found in the other twin

28
Q

What is an autoimmune attack?

A

When the immune system turns on itself rather than fighting an external infection

29
Q

Explain linking hypocretin to HLA

A

The autoimmune explanation could explain the involvement of HLA - mutations of HLA effect the immune system response making autoimmune conditions more likely and this may result in reduced numbers of hypocretin cells

30
Q

Who thought of the link between hypocretin and HLA?

A

Mignot (2001)

31
Q

Name 3 further studies supporting the hypocretin explanation of narcolepsy

A

1) Kilduff (2001)
2) Yanagisawa (2002)
3) Siegel (2002)

32
Q

Outline Kilduff (2001)

A

Bred narcoleptic Dobermans but didn’t reveal anything so looked into obesity - whilst examining brain scans of normal vs obese, discovered ‘new’ neurotransmitters present in the neurons in the hypothalamus - hypocretin - the hypocretin receptor sites vary in concentration in the 2 sets of scans so suggest it might be possible to produce a drug to treat obesity

33
Q

Outline Yanagisawa (2002)

A

Strain of mice without hypocretin neurons, assuming they eat and thus weigh less - found mice did eat significantly less but gained weight so filmed at night when they are normally very active and found spent most of their time asleep, and sudden onset of their sleep made it apparent that mice were narcoleptic

34
Q

Outline Siegel (2002)

A

Brain biopsies from dead narcoleptics and compared to ‘normal’ brain biopsies - found thousands of hypocretin cells in normal brains but 90% less in narcoleptic brains

35
Q

Name and explain 2 positive evaluative points for narcolepsy

A

1) Based on the biological approach - genetics, immune system & biochemistry so biological treatments
2) Hypocretin explanation seems to be the most promising due to the large amount of research supporting it and it being replicated in humans

36
Q

What is a big negative point about the hypocretin explanation of narcolepsy?

A

We don’t know what cause the low levels of hypocretin - not genetics

37
Q

Name 5 negative evaluative points for narcolepsy

A

1) Alternative - psychoanalytic
2) Biopsychosocial framework
3) Animal research
4) Reductionist
5) Deterministic

38
Q

Explain the psychoanalytic approach to narcolepsy

A

It is a way of disguising sexual fantasies and arousal, or a way of coping with them and reducing anxiety and distress they cause - but minority view

39
Q

Why use a psychosocial framework for narcolepsy?

A

Provide more explanatory value

40
Q

Why is using animal research for narcolepsy a bad thing?

A

Results cannot be extrapolated and generalised to humans as anatomy and physiology are different, and different sleep patterns - findings should be replicated in humans

41
Q

Explain why the explanations for narcolepsy are reductionist

A

They reduce a complex multi-system disorder to malfunctions of a specific biological system and ignores other possible factors - oversimplifies

42
Q

Explain why the explanations for narcolepsy are deterministic

A

They suggest if an individual has an abnormality, they cannot bring condition under control - may/may not be true but interesting to see how respond to behavioural interventions or CBT

43
Q

What is an IDA point for narcolepsy?

A

Real-world application

44
Q

Explain the real-world application for narcolepsy

A

Probably low levels of hypocretin cause narcolepsy so give a dose of hypocretin to sufferers but hypocretin molecule is relatively unstable and if given mouth or injection, broken down before it reaches the brain - even then this is not a cure as will only be controlled by taking the drugs - transplanting hypocretin-producing cells instead may result in a cure