On behalf of the European Narcolepsy Network (EU-NN), Zhang and colleagues¹ recently discovered a new incidence peak in narcolepsy in 2013. The researchers used predictive modelling on the EU-NN database to assess possibly increases in incidence rates of narcolepsy type 1 over the past two decades. They interestingly reported a new incidence peak in 2013 that had not been described before. This peak turned out to be present when including the entire EU-NN database, with strongest effects in France, Italy, the Netherlands and Switzerland. Interestingly the newly identified peak in 2013 was age-specific for children where most of these children had a typical subacute disease onset with rapid onset of cataplexy. This is consistent with the autoimmune-mediated form of narcolepsy type 1.

The authors also replicated the 2010 incidence peak in other European countries than France and Finland where it had not been described before, including the Netherlands, Germany, Spain and Czech Republic. While some European countries previously found an association between the narcolepsy type 1 incidence increase in 2010 and the swine influenza (H1N1) vaccination Pandemrix, reports from Asian countries suggested the H1N1 virus itself to be linked to the increased narcolepsy type 1 incidence.

The new 2013 incidence peak is likely not related to Pandemrix as it was not used after 2010. A role for H1N1 virus in 2013 is possible as it has recirculated in the years after the pandemic of 2009, but involvement of other/new viruses or other environmental factors is similar possible. In the countries with the 2013 narcolepsy type 1 increase, the 2012-2013 influenza season was severe compared to other years with circulation of different influenza types. Future studies are needed to find the exact relationship between infection, vaccination and development of autoimmune-mediated narcolepsy type 1.

For more information, please find the report here: https://doi.org/10.1093/sleep/zsaa172.