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DISCUSS EXPLANATIONS
OF NARCOLEPSY
Introduction
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Narcolepsy is a Ddyssomnia
Characteristics
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Excessive daytime sleepiness
Cataplexy
Hypnogogic hallucinations
Sleep paralysis
Sleep attacks
Clinical diagnosis – excessive daytime sleepiness + 1 or more of the other
symptoms
Effects 1 in 2000
Occurs in teens and adulthood
Explanations
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Genetic
Auto-immune response to viruses
Outline of disorder
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Reduction in hypocretin (Hcrt) secreting cells
Hypothalamus
Reduction in Hcrt released into spinal chord
Hcrt is a neurotransmitter
Reduction of around 80% of functioning cells
This neurotransmitter controls the descent into sleep
through the stages
Narcoleptics move between waking and REM sleep
Genetic outline
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Mutation reduces productivity of hcrt secreting cells
Passed down generations in DNA
The closer you are related to a sufferer the more likely
you are to get the illness
Relatedness is expressed through concordance rates
This explanation predicts that there would be a high
concordance between sufferers and close relatives and
lower concordance with more distance relatives
High concordance for MZ twins compared to DZ twins
Evaluation
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Supported by research
Narcolepsy gene passed down through certain
breeds of dog
Gene that causes narcolepsy in dogs isolated
However further research showed in humans out of
16 MZ twins only in 4 cases were both narcoleptic
Lowers internal validity of the explanation
Cannot use this explanation to help understand
narcolepsy or to help develop new treatments
Issues & Debates (1)
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Uses non-human animals to draw conclusions
In this case the results cannot be extrapolated to
humans
Any new treatments cannot be used in humans
No justification in using dogs/NHA in human
narcolepsy research
No continuity of function
Using NHA for narcolepsy isn’t useful
Auto-immune Outline
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Caused by a mutation in the HLA gene
Trib-2 is an antibody released into the body
Triggered by illness
In narcoleptics trib-2 destroys hcrt-secreting cells
Deficiency in hcrt triggers narcolepsy
Evaluation 1
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Overeem et al (2008) found that 90% of
narcoleptics have faulty HLA gene
Cases of H1N1 (flu virus) coincide with new cases of
narcolepsy
Supports idea that it is the HLA gene that triggers
narcolepsy
Increases the reliability of this explanation
Can use this explanation to help develop new
treatments for narcolepsy
Evaluation 2
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Explains why narcolepsy isn’t usually present in
childhood
Also helps explain why there is a lack of
predictability of genetic evidence
Increases the internal validity of explanation
Evaluation 3
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Doesn’t explain the 10% of narcoleptics without the
HLA defect
Lowers internal validity of this explanation
Cannot use this explanation to explain every case
Some treatments developed cannot be used on
everybody
Issues & Debates (2)
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Uses biological reductionism
Treats the symptoms rather than the cause
Further research shoes that environmental factors such
as stress and illness induce narcoleptic attacks
Lifestyle changes can avoid attack triggers
Stress
 illness
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Interactionist approach
Possible to treat symptoms as well as cause of attack
Empowerment of sufferers