What is the Cause?

A person with an autoimmune disease has an immune system that attacks healthy cells. Examples of autoimmune diseases include Multiple Sclerosis, Type 1 Diabetes, and Mellitus Rheumatoid Arthritis. An interesting and significant finding from recent studies show that Narcolepsy may be caused by an autoimmune attack in the body as well. Therefore, narcolepsy may be primarily an autoimmune disease. But is it really?

Researchers determined that the two possible causes of narcolepsy are lack of hypocretin and a different form of the human leukocyte antigen. Hypocretin is a hormone that allows animals and humans to stay awake and alert. Even though the brain cells and system that create hypocretin cells are still in narcoleptic patients, the cells are missing, which can mean one thing: something has to destroy them. Researchers now believe that they are destroyed by the immune system in an autoimmune attack.

This image below shows the difference between the number of hypocretin cells in the hypothalamus of narcoleptic and a non-narcoleptic person. As you can see, a narcoleptic has predominantly less hypocretin cells.

 People with narcolepsy also have a different type of the human leukocyte antigen. HLA allows the immune response to act and permits the immune system to fight off pathogens. Although many studies found no relationship between narcolepsy and the immune system, Professor Mignot from Stanford University was curious and suspected that there is indeed a link. As a result, he created a study to test his idea. Along with Joachim Hallmayer and other colleagues, they focused their analysis on the DNA of four thousand participants. Half of the participants shared the same HLA variant linked to narcolepsy and the other half were actual narcoleptics. According to the results, narcoleptics share a gene that allows T cells to act and destroy pathogens. The gene also permits T cells to know how to respond to intruders that are brought to them from HLA molecules.  According to Nature Genetics, the researchers concluded that T cells and HLA both work together to kill off hypocretin cells in narcoleptics.

Although this is significant news, there are still some doubts and curiosities. According to Mignot,  "We don't know why bodies go haywire and start attacking themselves". Mignot’s study fails to explain why hypocretin cells attract T cells. Also, it doesn’t explain the purpose of the destruction. Despite these failures to answer these questions, knowing that narcolepsy may be caused by an autoimmune attack allow guide researchers to find the cause for narcolepsy and to create more treatments for the victims.