Explanations for Narcolepsy Flashcards
What is the essay plan for Narcolepsy?
What is Narcolepsy Early Explanations 1960's - REM AO1 1960's - REM AO2 1980's - HLA AO1 1980's - HLA AO2 Recent Research - Hypocretin AO1 Recent Research - Hypocretin AO2 Real World Application
What is Narcolepsy?
Narcolepsy is a sleep disorder where individuals experience sudden and uncontrollable attacks of sleep at irregular and unexpected times, which may last seconds or minutes. An episode is often triggered by stressful situations.
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What was the early approach to explaining Narcolepsy?
Key Study
Lehrman and Weiss 1943
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What was the early approach to explaining Narcolepsy?
A very early approach to explaining narcolepsy focused on psychological issues. For example, Lehrman and Weiss 1943 suggested that sudden attacks of sleepiness disguise sexual fantasies
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What was the 1960’s REM approach to explaining Narcolepsy?
One of the classic symptoms of narcolepsy is loss of muscle tone (called cataplexy). This is similar to what happens during REM sleep. In addition, during te daytime, narcolepstics often experience intrusions of REM-type sleep (hallucinations). At night narcoleptics have abnormal REM sleep. Therefore, in the 1960s an explanation offered for narcolepsy was that it was caused by a malfunction in the system that regulates REM sleep
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What was the 1960’s REM approach to explaining Narcolepsy?
Key Studies
Vogel 1960
Siegel 1999
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What was the 1960’s REM approach to explaining Narcolepsy?
The REM explanation was supported by Vogel 1960 who observed REM sleep at the onset of sleep in a narcoleptic patient, whereas it more commonly occurs later in the cycle of sleep stages. This was further supported by recording of neuron activity in the brainstem of narcoleptic dogs. This showed that cataplexy (lack of muscle tone) co-occured with brain cell activity that usually only occurs in REM sleep (Siegel, 1999). However, in general research support has not been convincing
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What was the 1980’s HLA approach to explaining Narcolepsy?
Key Studies
Honda et al 1983
Standford Medical Center, 2012
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What was the 1980’s HLA approach to explaining Narcolepsy?
In the 1980’s research pointed in a new direction, suggesting that narcolepsy was linked to a mutation of the immune system. Honda et al 1983 found increased frequency of one type of HLA (human leukocyte antigen) in narcoleptic patients. HLA molecules are found on the surface of white blood cells and coordinate the immune response. Recent research has found that more than 90% of people suffering from narcolepsy with cataplexy had been found to have the HLA variant HLADQB10602 (Stanford Medical Center, 2012).
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What was the 1980’s HLA approach to explaining Narcolepsy?
Key Studies
Mignot et al 1997
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What was the 1980’s HLA approach to explaining Narcolepsy?
The HLA explanation for Narcolepsy is weakened by the fact that the specific HLA variant (HLADQB10602) found most commonly in narcoleptics is not found in all narcoleptics. The same HLA variant is also reasonably common in the general population (Mignot et al 1997). Both of these facts mean that the HLA variant cannot be the only cause of Narcolepsy
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What does the recent research suggest about the hypocretin explanation for explaining Narcolepsy?
Most recently, research has uncovered another link, this time between a neurotransmitter and narcolepsy. The neurotransmitter is hypocretin (or orexin). Hypocretin regulates sleep and wakefulness through interactions with systems that regulate emotion and homeostasis in the hypothalamus (Sakurai, 2007). Normally there are about 10,000 to 20,000 hypocretin producing cells in the hypothalamus but in many narcoleptics a large number of these these are missing resulting in low levels of hypocretin
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What does the recent research suggest about the hypocretin explanation for explaining Narcolepsy?
Key Studies
Sakurai, 2007
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What does the recent research suggest about the hypocretin explanation for explaining Narcolepsy?
Evidence of Lower levels
Key Studies
Lin et al 1999
Nishnino et al 2000
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What does the recent research suggest about the hypocretin explanation for explaining Narcolepsy?
Evidence of Lower levels
Reserch evidence to support the idea that low levels of hypocretin play a role in narcolepsy first came from narcoleptic dogs who were found to have a mutation in a gene on chromosome 12. This mutation had the effect of disrupting the processing of hypocretin (Lin et al, 1999). The findings from narcoleptic dogs have been confirmed in human studies, for example, it was found that human narcoleptics had lower levels of hypocretin than normal in their cerebrospinal fluid (Nishnino et al, 2000).
