Medical exposures in youth and the frequency of narcolepsy with cataplexy: a population-based case-control study in genetically predisposed people.

Epidemiological observations suggest that exposures in youth may trigger narcolepsy in genetically predisposed individuals. In this population-based case-control study, we sought to identify all prevalent cases of narcolepsy with cataplexy aged 18-50 years as of 1 July 2001, in King County, Washington. The 45 eligible cases who were DQB1*0602-positive were compared with 95 controls with this allele, identified through random-digit dialing and buccal smears. Cases and controls were interviewed in person about physician-diagnosed infectious and non-infectious illnesses, immunizations, head trauma and parasomnias or psychiatric problems during youth. Narcolepsy with cataplexy was more frequent in African-Americans and in poorer households. Adjusting for these factors, the condition was 5.4-fold more common [95% confidence interval (CI) = 1.5-19.1] among people reporting a physician-diagnosed strep throat before the age of 21 years. No other significant associations with childhood diseases, immunizations or head trauma were found. However, prevalence was increased 16.3-fold (95% CI = 6.1-44.1) in subjects who reported having had 'night terrors'. Strep throat may be related to narcolepsy with cataplexy in genetically susceptible individuals. The association with night terrors could simply reflect early symptoms of narcolepsy, or they could be a prodromal sign of disturbed sleep physiology.