Narcolepsy is a rare sleep disorder thought to be caused by a combination of influences, including hereditary and environmental factors. Scientists also suspect that infections play a role in the development of narcolepsy — including streptococcal pharyngitis, also known as strep throat.
A research study found that people younger than 21 years with a history of strep throat had a five-times higher risk of developing narcolepsy than those with no history of strep throat infection. This and other research findings have led scientists to suspect that strep throat infection may play a role in the development of narcolepsy.
Some members of MyNarcolepsyTeam have also questioned whether strep throat was a factor in their development of narcolepsy. “I read a while ago (about two weeks or so) that one of the things that can contribute to narcolepsy is tied to recurring issues with strep throat, which was something that I had growing up,” commented one member.
While strep throat is a relatively common bacterial infection in children, narcolepsy is rare, with a prevalence of about 25 to 50 people per 100,000 people in the U.S. An infection with strep throat will not definitively cause narcolepsy, and there’s no reason to fear that a case of strep throat will lead to narcolepsy.
The research exploring connections between narcolepsy and strep throat is correlational, or showing connections. It does not prove causation between strep throat infection and narcolepsy. However, since narcolepsy can affect quality of life, researchers focus on environmental risk factors like strep throat to help in the prevention and treatment of narcolepsy.
Strep throat is a throat infection caused by the bacteria Streptococcus pyogenes. The condition is characterized by signs and symptoms such as:
The infection occurs more commonly in children and adolescents. Strep is responsible for about 20 percent to 30 percent of sore throats in children, and 5 percent to 15 percent of sore throats in adults. Strep throat is more common during the winter when there is an increase in other respiratory infections, like colds and the flu.
Strep throat is contagious and there is not yet a vaccine to prevent it. However, strep responds well to treatment with oral antibiotics, pain killers, and fever reducers. You can reduce your risk of contracting strep throat through practices like diligent hand washing, especially in the winter months.
Symptoms of narcolepsy are caused by a lack of chemicals called hypocretins in the brain. Hypocretins help regulate the sleep-wake cycle. When the brain is low on these chemicals, it has trouble regulating when a person should be asleep or awake. However, it is not fully understood what causes a loss of hypocretins in people who develop narcolepsy.
There are also clear hereditary influences in narcolepsy. A gene important for the function of the immune system, called human leukocyte antigen (HLA) DQB1*06:02, is found in most people (95 percent) with narcolepsy. This gene is associated with an increased risk of narcolepsy.
There are several other genes that affect a person’s risk of developing narcolepsy. However, because not everyone with these specific genes will develop narcolepsy, scientists suspect that other factors are at play in determining who will develop narcolepsy.
Scientists believe that narcolepsy is an autoimmune disease. An autoimmune disease or autoimmune disorder is one in which the immune system mistakenly attacks healthy tissue and cells. In cases of narcolepsy, the immune system attacks hypocretin-producing neurons (cells) in the hypothalamus, a section of the brain. If this process causes a reduction in the production of hypocretins, narcoleptic symptoms may develop.
Autoimmune responses can be triggered by different influences, and one of the influences thought to play a role in triggering narcolepsy is infection.
Several major research findings have helped support the idea that infections like strep may trigger an autoimmune response that leads to narcolepsy.
For example, a research study published in Sleep found that 65 percent of people with narcolepsy had immune response markers indicating past strep throat infections, compared to only 26 percent of people without narcolepsy.
The fact that narcolepsy diagnoses usually increase in the late spring or early summer may indicate that narcolepsy was brought on by an infection that happened during the winter months. A research study published in the Annals of Neurology found that narcolepsy diagnoses were associated with seasonal patterns of upper airway infections, like after the H1N1 pandemic.
There have also been case studies linking narcolepsy and strep throat infection. Case studies are those that examine a specific case or instance of disease and aim to understand what caused it. Case studies of children with narcolepsy published in Sleep Science and the Journal of Clinical Sleep Medicine have concluded that streptococcal infection likely triggered narcolepsy onset in children who were also genetically susceptible.
Other evidence of infection potentially leading to narcolepsy comes from an event that occurred from 2010 to 2011 in Finland: Dozens of children developed narcolepsy after receiving a very potent form of an H1N1 influenza vaccine called Pandemrix. All of the children who developed narcolepsy also had the HLA-DQB1*06:02 gene. It’s important to note that the vaccine did not necessarily cause narcolepsy, and the study only shows an association between vaccination and the disease onset of narcolepsy. The Pandemrix vaccine was never used in the U.S. and is no longer licensed for use anywhere.
The associations found between strep throat infection and the onset of narcolepsy in the research create compelling theories about the cause of narcolepsy. The research on this topic is still ongoing, and no conclusive statements regarding the cause of narcolepsy can be made.
While strep infection can be effectively treated with antibiotics, there are several ways to help prevent its transmission:
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