Narcolepsy onset is seasonal and increased following the 2009 H1N1 pandemic in china
Article first published online: 22 AUG 2011
Copyright © 2011 American Neurological Association
Annals of Neurology
Volume 70, Issue 3, pages 410–417, September 2011
How to Cite
Han, F., Lin, L., Warby, S. C., Faraco, J., Li, J., Dong, S. X., An, P., Zhao, L., Wang, L. H., Li, Q. Y., Yan, H., Gao, Z. C., Yuan, Y., Strohl, K. P. and Mignot, E. (2011), Narcolepsy onset is seasonal and increased following the 2009 H1N1 pandemic in china. Ann Neurol., 70: 410–417. doi: 10.1002/ana.22587
- Issue published online: 8 SEP 2011
- Article first published online: 22 AUG 2011
- Manuscript Accepted: 2 AUG 2011
- Manuscript Revised: 31 JUL 2011
- Manuscript Received: 3 JUN 2011
- National Science Foundation of China. Grant Number: 81070069
- Sino-German Center for Research Promotion. Grant Number: GZ538
- Beijing Municipal Science and Technology Commission. Grant Number: D1011000050010029
Narcolepsy is caused by the loss of hypocretin/orexin neurons in the hypothalamus, which is likely the result of an autoimmune process. Recently, concern has been raised over reports of narcolepsy in northern Europe following H1N1 vaccination.
The study is a retrospective analysis of narcolepsy onset in subjects diagnosed in Beijing, China (1998–2010). Self-reported month and year of onset were collected from 629 patients (86% children). Graphical presentation, autocorrelations, chi-square, and Fourier analysis were used to assess monthly variation in onset. Finally, 182 patients having developed narcolepsy after October 2009 were asked for vaccination history.
The occurrence of narcolepsy onset was seasonal, significantly influenced by month and calendar year. Onset was least frequent in November and most frequent in April, with a 6.7-fold increase from trough to peak. Studying year-to-year variation, we found a 3-fold increase in narcolepsy onset following the 2009 H1N1 winter influenza pandemic. The increase is unlikely to be explained by increased vaccination, as only 8 of 142 (5.6%) patients recalled receiving an H1N1 vaccination. Cross-correlation indicated a significant 5- to 7-month delay between the seasonal peak in influenza/cold or H1N1 infections and peak in narcolepsy onset occurrences.
In China, narcolepsy onset is highly correlated with seasonal and annual patterns of upper airway infections, including H1N1 influenza. In 2010, the peak seasonal onset of narcolepsy was phase delayed by 6 months relative to winter H1N1 infections, and the correlation was independent of H1N1 vaccination in the majority of the sample. ANN NEUROL 2011;