Narcolepsy generally begins in adolescence, but the age of the first occurrence varies enormously. The cause of narcolepsy remains unknown, but probably involves an interaction between genetic and environmental factors, which trigger the alteration of the hypocretin system leading to sleep disturbances. Narcolepsy is highly related to HLA subtypes.11 The familial form

of narcolepsy cataplexy is only observed in 10% of cases. The diagnosis of narcolepsy Inhibitors,research,lifescience,medical is essentially clinical, but also involves a nocturnal polysomnographic recording followed by an MSLT, during which sleep latency should be below 8 min with at least two SOREMPs. The diagnosis is reinforced by the finding of a serological Inhibitors,research,lifescience,medical DR2-DQ1 HLA typing (more Angiogenesis inhibitor precisely DRB1*1501-DQB1*0602). Such an oligonucleotidic typing is found in 92% of Caucasian narcoleptics, compared with only 20% in the general population. More recently, narcolepsy has been related to impaired function of hypocretin-secreting neurones located in the laterodorsal hypothalamus. In the cerebrospinal fluid (CSF) of patients, hypocretin-1 concentration Inhibitors,research,lifescience,medical drops12 and the postmortem pathological examination of the brain reveals the disappearance of hypocretinergic neurons.13,14 An autoimmune origin is one hypothesis. However,

like in the canine narcolepsy model developed at Stanford, in which a mutation of the gene coding the receptor 2 of hypocretin is present,15 a mutation of the gene coding for preprohypocretin has been reported in one atypical and severe case of human narcolepsy13 Narcolepsy without Inhibitors,research,lifescience,medical cataplexy has been described as a phenotypic variant. The clinical diagnostic criteria are similar to that of narcolepsy with cataplexy, except that the cataplexy is not present. However, the association with the HLA DQB 1*0602 is weaker and the decrease in CSF

hypocretin is less frequently encountered. A common pathophysiology is still a matter of debate. There is no cure for narcolepsy. None of the currently available medications enables patients to maintain a permanent Inhibitors,research,lifescience,medical normal state of alertness. However, the most disabling symptoms, excessive daytime sleepiness and cataplexy, can be controlled in most patients. In more recent years, amphetamine derivatives have frequently been replaced by modafinil for the treatment of excessive daytime sleepiness.16 In cases of persistent excessive daytime sleepiness, methylphenidate, amphetamine, and mazindol (a derivate of amphetamine) may be of value. The Casein kinase 1 control of cataplexy is still obtained with antidepressants: tricyclics (including imipramine, desipramine, clomipramine, and protriptyline) and also selective serotonin reuptake inhibitors (including fluoxetine and sertraline) and serotonin and noradrenaline reuptake inhibitors (venlafaxine), which do not have the side effects of tricyclics. If the symptoms persist, mazindol may be used since it is active on both diurnal sleepiness and cataplexy.