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Who gets Narcolepsy?

Narcolepsy is not rare, but it is an under-recognised and under-diagnosed condition. The disorder is estimated to affect about one in every 2,000 Americans. But the exact prevalence rate remains uncerntain, and the disorder may affect a larger segment of the population.

Narcolepsy appears throughout the world in every racial and ethnic group, affecting males and females equally. But prevalence rates vary among populations. Compared to the U.S. population, for example, the prevalence rate is substantially lower in Israel (about one per 500,000) and considerably higher in Japan (about one per 600).

Most cases of narcolepsy are sporadic-that is, the disorder occurs independently in individuals without strong evidence of being inherited. But familial clusters are known to occur. Up to 10 percent of patients diagnosed with narcolepsy with cataplexy report having a close relative with the same symptoms. Genetic factors alone are not sufficient to cause narcolepsy. Other factors-such as infection, immune-system dysfunction, trauma, hormonal changes, stress-may also be present before the disease develops. Thus, while close relatives of people with narcolepsy have a statistically higher risk of developing the disorder than do members of the general population, that risk remains low in comparison to diseases that are purely genetic in origin.

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