Does H1N1 influenza cause narcolepsy?
Based on the idea that narcolepsy is caused by autoimmune destruction of hypocretin-orexin neurons in the hypothalamus and concerns raised over reports that the onset of narcolepsy can follow H1N1 vaccination, researchers from the Department of Pulmonary Medicine at Beijing University People's Hospital in Beijing , China , have published a retrospective analysis to address this proposed relationship.
The researchers collected self-reported month and year of onset of narcolepsy from 629 patients, 86 of whom were children, and analyzed the monthly variation in the onset of narcolepsy. In addition, 182 patients who had developed narcolepsy after October of 2009 were asked for a vaccination history. They found the occurrence of narcolepsy to be seasonal with a significant influence by month and calendar year. The onset was least frequent in November and most frequent in April, with a 6.7-fold increase in cases between trough and peak. They also found a 3-fold increase in narcolepsy onset following the 2009 H1N1 winter influenza pandemic. Only 8 of 142 of these patients recalled receiving the H1N1 vaccination. They were able to show a significant 5- to 7-month delay between the seasonal peak of influenza (H1N1 infections) and the peak in narcolepsy onset occurrences. The researchers concluded that 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 largely independent of H1N1 vaccination.
Upper airway infection seems more and more possible as a trigger to narcolepsy, so the answer would be yes probably H1N1 can cause narcolepsy.