Emmanuel Mignot, who is the director of the Stanford Center for Sleep Sciences and Medicine has long believed that some onsets of Narcolepsy could be caused by a confused autoimmune response in the body of those suffering from influenza or other infections. Basically, the body mistakes one of its own chemicals (which helps to regulate sleep) with a protein present in the flu. Mignot says this idea started with a simple hunch, but his thoughts have recently been confirmed.
The history of Narcolepsy and the flu
There was a wave of narcolepsy diagnoses in Europe following the swine flu outbreak of 2009. There was a vaccine for the virus but after seeing that cases of narcolepsy were rising following the widespread distribution of the vaccine, it was withdrawn. It’s important to note that this same pattern was not seen in the United States.
Beijing University also tracked narcolepsy cases which occurred in China between the years of 1998 and 2010. This data showed that more people were diagnosed with narcolepsy after the peak of viral infections was over each year. This spike in viral infections occurred every winter and the vast majority of narcolepsy diagnoses were given in the spring and the summer. This study also found an additional jump in narcolepsy diagnoses in China after the 2009 H1N1 pandemic.
The flu infections had to have something to do with the occurrence of narcolepsy, but researchers couldn’t figure out exactly what. Ultimately, there had to be antigens which were triggering the immune system to have such an extreme response following infection. But no scientist could discover what these antigens were.
In addition to the flu, Mignot had also seen narcolepsy diagnoses after strep infections. He was confident that some type of immune reaction had to be present for an autoimmune disease like narcolepsy to occur. So, he and his team began to search for antigens which may be causing this reaction.
They screened microscopic samples of the flu from blood samples of patients who had narcolepsy. The goal was to document any sign of T cell reactivity. The problem is, there are billions of T cells and anyone of them theoretically could produce this reaction. Mignot described it as trying to find a needle in a haystack.
But his team did it. They were able to find the T cells that were recognizing the flu virus as well as hypocretin. Hypocretin helps to regulate sleep. It’s previously been discovered that those who have narcolepsy have lost 90% of their cells that contain hypocretin. Mignot was able to uncover that hypocretin and one of the sequences of amino acids in the flu looks similar, causing the body to react to them the same way toward them.
Therefore, a flu virus could trigger narcolepsy. Additionally, Mignot found that even a flu vaccine could produce this same reaction.
These findings were published in the Proceedings of the National Academy of Sciences
The deal with flu vaccines
So why did Europe experience such a pandemic of the flu, and then narcolepsy diagnoses while the United States did not? It’s because many of the new narcolepsy diagnoses in Europe were caused by the flu vaccine, not the flu itself. Since the flu was spreading quickly across the continent, companies were moving quickly to come up with a vaccine. GlaxoSmithKline used an immune-booster in their vaccine because they didn’t have adequate time to grow the virus first. However, Mignot thinks their formulation was too strong, causing some of the narcolepsy diagnoses. That said, some of the people who had the vaccine from GlaxoSmithKline may have already had the virus in their body, so this assumption cannot be confirmed.
In the United States, a different version of vaccine was used and there was no linkage between the vaccine and narcolepsy.
Mignot hopes that in the future, flu vaccine developers will refrain from including certain proteins which illicit autoimmune responses. However, he also makes it clear that vaccines are still extremely important and that overall the risk of adverse reactions to a vaccine is very small. Mignot says that ultimately, there is nothing which is beneficial that doesn’t also carry some risk.
However, that doesn’t mean there aren’t precautions we can take in the future, fueled by our ever-increasing knowledge.
You can read more about these findings and Mignot’s narcolepsy research here.