The epidemiology of narcolepsy in Olmsted County, Minnesota: a population-based study

STUDY OBJECTIVES: To determine the age- and sex-specific incidence rates and prevalence of narcolepsy in a United States community. DESIGN: The records-linkage system of the Rochester Epidemiology Project was utilized to ascertain all patients with narcolepsy seen in Olmsted County, Minnesota between 1960 and 1989. Age- and sex-specific incidence rates were calculated, using census data. Prevalence of narcolepsy on January 1,1985 was calculated. SETTING: N/A. PATIENTS OR PARTICIPANTS: Community patients diagnosed with narcolepsy by a validated set of diagnostic criteria. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: The incidence rate per 100,000 persons per year was 1.37 (1.72 for men and 1.05 for women). The incidence rate was highest in the 2nd decade, followed in descending order by the 3rd, 4th and 1st decades. The prevalence on January 1, 1985 was 56.3 per 100,000 persons. Approximately 36% of prevalence cases did not have cataplexy. CONCLUSIONS: Narcolepsy is not a rare disorder. It appears to be commoner in men. It originates most commonly in the 2nd decade. Narcolepsy without cataplexy is an important subgroup, warranting further study.