Infections May Trigger Narcolepsy

In May the Sleep Education Blog reported that narcolepsy may be an autoimmune disorder. Research suggests that narcolepsy may develop when the immune system attacks and destroys hypocretin-producing brain cells by mistake. Hypocretin is a hormone that helps promote wakefulness.

But what causes this immune system response? A study in the Aug. 1 issue of the journal Sleep shows that bacterial infection may be one trigger.

The study involved 200 people with narcolepsy and 200 healthy controls. They were recruited from the U.S., the Czech Republic, Italy and South Korea. Their blood was tested for antibodies that are markers of bacterial infection.

Results show that the levels of antibodies related to “streptococcus” were much higher in people with narcolepsy. These levels were highest when blood was drawn soon after narcolepsy symptoms began.

Streptococcus is the name of a group of bacteria. Some types of the bacteria can cause disease in humans; examples include scarlet fever, strep throat and tonsillitis.

The authors note that the levels of anti-streptococcal antibodies vary widely across people groups. About 90 percent of the people with narcolepsy in this study were Caucasian; so the study needs to be replicated among other ethnic groups.

But the results show that streptococcal infections are probably an important trigger for narcolepsy.