Prevalence of narcolepsy symptomatology and diagnosis in the European general population

To determine the prevalence of narcolepsy in the general population of five European countries (target population 205,890,882 inhabitants).

Overall, 18,980 randomly selected subjects were interviewed (participation rate 80.4%). These subjects were representative of the general population of the UK, Germany, Italy, Portugal, and Spain. They were interviewed by telephone using the Sleep-EVAL expert system, which provided narcolepsy diagnosis according to the International Classification of Sleep Disorders (ICSD).

Excessive daytime sleepiness was reported by 15% of the sample, with a higher prevalence in the UK and Germany. Napping two times or more in the same day was reported by 1.6% of the sample, with a significantly higher rate in Germany. Cataplexy (episodes of loss of muscle function related to a strong emotion), a cardinal symptom of narcolepsy, was found in 1.6% of the sample. An ICSD narcolepsy diagnosis was found in 0.047% of the sample: The narcolepsy was severe for 0.026% of the sample and moderate in 0.021%.

This is the first epidemiologic study that estimates the prevalence of narcolepsy in the general population of these five European countries. The disorder affects 47 individuals/100,000 inhabitants.