A case-control study of the environmental risk factors for narcolepsy.
BACKGROUND
Despite the acknowledged importance of environmental risk factors in the etiology of narcolepsy, there is little research on this topic. This study sought to fill this gap in the literature and assess the risk of stressors and infectious diseases using a case-control study.


METHODS
Cases (n = 63) were recruited through the Stanford Center for Narcolepsy. All were HLA-DQB1*0602 positive, met conventional Multiple Sleep Latency Test criteria, and reported unambiguous cataplexy. Controls (n = 63) were nonrelated family members of cases and local community members. A self-administered questionnaire was used to assess the frequency and timing of possible risk factors.


RESULTS
Of the infectious diseases examined, only flu infections and unexplained fevers carried a significant risk. Several of the stressors carried a significant risk including a major change in sleeping habits. When the timing of all risk factors was considered, exposure prior to puberty increased the risk for developing narcolepsy.


CONCLUSIONS
These findings emphasize the importance of environmental risk factors in the etiology of narcolepsy. This highlights the need for further research on this aspect of narcolepsy so a complete understanding of a disorder that affects 1 in 2,000 individuals can emerge.
Department of Psychology, University of Southern Mississippi, Hattiesburg, Mississippi, USA. dante.picchioni@amedd.army.mil
Dante
D
Picchioni
Chris R
CR
Hope
John R
JR
Harsh
D000328:Adult; D002140:California; D002385:Cataplexy / Q000453:epidemiology* / Q000209:etiology / Q000235:genetics; D003141:Communicable Diseases / Q000150:complications / Q000453:epidemiology*; D020920:Dyssomnias / Q000150:complications / Q000453:epidemiology; D004781:Environmental Exposure / Q000009:adverse effects / Q000706:statistics & numerical data*; D005260:Female; D005335:Fever of Unknown Origin / Q000150:complications / Q000453:epidemiology; D006683:HLA-DQ Antigens / Q000235:genetics; D059866:HLA-DQ beta-Chains; D006306:Health Surveys; D006801:Humans; D007251:Influenza, Human / Q000150:complications / Q000453:epidemiology; D008016:Life Change Events; D008297:Male; D008562:Membrane Glycoproteins / Q000235:genetics; D008922:Mississippi; D009290:Narcolepsy / Q000453:epidemiology* / Q000209:etiology / Q000235:genetics; D012307:Risk Factors; D013223:Statistics as Topic
D006683:HLA-DQ Antigens; D059866:HLA-DQ beta-Chains; C069051:HLA-DQB1 antigen; D008562:Membrane Glycoproteins