Two years ago, Stanford sleep researcher Emmanuel Mignot, MD, PhD, made headlines when he showed that narcolepsy is an autoimmune disease, caused when patients’ immune systems kill the neurons that produce the protein hypocretin. The current thinking is that a person is genetically predisposed to the disease, and some environmental factor kicks his or her immune system into action.
Now, Mignot and colleagues have a paper in Annals of Neurology that suggests one such trigger: winter airway infections such as H1N1. In a study involving more than 900 narcolepsy patients in China, the researchers found that a peak in narcolepsy cases occurred five to seven months after a peak in flu/cold or H1N1 infections in the country. These winter infections, the authors wrote, appear to have initiated or reactivated an immune response that leads to narcolepsy.
“We’re much closer to understanding what’s happening in the autoimmune destruction of hypocretin cells,” Mignot told me.
In other findings, the researchers observed no link between H1N1 vaccinations and narcolepsy, which is quite different than what has been seen in Europe. (In Finland, for example, children who received the Pandemrix H1N1 vaccine, which contains two additives to invoke a stronger immune response, faced a 9-fold increased risk of the disease.) China uses a different, more mild vaccine, so clearly more study on narcolepsy and vaccines is needed. But in the meantime:
Mignot said the work suggests that getting vaccinated and avoiding influenza may provide a protective benefit to patients. He said, “It’s very possible that being vaccinated with a mild vaccine [one without additives] blocks you from getting a big infection that could increase your risk of narcolepsy.”