Narcolepsy Research - FAQs

1- What is the cause of narcolepsy?
Recent studies have shown that narcolepsy with cataplexy is usually caused (>90%) by the lack of two related brain chemicals called "hypocretin-1" and "hypocretin-2". The cause of narcolepsy without cataplexy is still under investigation.

2- What are these so-called hypocretin (orexin) molecules?
Hypocretins (orexins) were discovered by two groups of researchers almost simultaneously, hence the two names "hypocretins" and "orexins". The first group called them "hypocretin-1" and "hypocretin-2" after discovering that the molecules were found only in the hypothalamus and had some weak resemblance with the gut hormone secretin. Only 10,000-20,000 cells in the entire human brain (out of many billions) secrete these specific hypocretin molecules. The hypothalamus, a region localized deep in the base of the brain, regulates many basic functions such as the release of hormones, blood pressure, sex, food intake regulation and sleep. The subregion of the hypothalamus containing the hypocretin cells was known to be especially important for the regulation of feeding. These molecules were thus first hypothesized to be important in feeding regulation. In fact, the second group that discovered the hypocretin molecules called them "orexin A and orexin B" (from orexis=appetite in grec) and suggested that they stimulated appetite. Orexins and hypocretins are thus interchangeable terms and the scientific community is divided on what is the best name to use.

3- How can I have my hypocretin levels measured?
Hypocretin-1 (but not 2) can be measured in the cerebrospinal fluid (CSF) but not in the blood or in any other peripheral tissue. A lumbar puncture is required to collect CSF. Most patients with narcolepsy-cataplexy have no hypocretin-1 molecules in their CSF. If you are interested in having your CSF hypocretin levels measured, please contact Mali Einen at the Center for Narcolepsy.

4- How do you collect cerebrospinal fluid (CSF)?
To draw CSF requires a lumbar puncture (spinal tap). This is a safe but not completely insignificant procedure (the main problem is that temporary headaches can occur in about 5% of the cases following the procedure). The procedure is a little similar to an epidural anesthesia (actually safer and easier), is used a lot by neurologists to exclude many neurological problems such as brain hemorrhage, brain infections, multiple sclerosis, etc... We have tried to measure hypocretins in other tissues such as blood but this molecule probably exists in sufficient amount only in the brain and the CSF. Clearly, some effort should be devoted in measuring hypocretin levels more easily.