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Why narcolepsy is an autoimmune condition

Previous research has suggested that narcolepsy may be an autoimmune condition. Now, a new paper published in the journal Nature Communications finds additional evidence that this may be the case.

man asleep on his desk

Narcolepsy involves ‘sleep attacks’ that can interfere with daily activities.

Narcolepsy is a chronic neurological condition that affects a person’s sleep-wake cycle.

The condition makes people feel excessively tired during the day. It may also cause them to experience sudden “sleep attacks,” during which an overwhelming desire to sleep can interfere with daily activities.

According to the National Institute of Neurological Disorders and Stroke, between 135,000 and 200,000 people in the United States are currently living with narcolepsy.

Some of these people also experience cataplexy — that is, “a sudden loss of muscle tone” that usually occurs in response to strong emotions such as laughter or surprise.

Researchers have divided narcolepsy into two subcategories: type 1, which is more common and also involves cataplexy, and type 2, wherein people do not have cataplexy.

In narcolepsy type 1, the neurons that produce a sleep-inducing chemical called hypocretin are damaged. Hypocretin is a neurotransmitter that helps keep the brain alert and stops it from entering the dreaming phase of sleep at the wrong time.

Previous studies have found that a class of immune cells called CD4 T are autoreactive in narcolepsy. This means that they see the body’s own hypocretin-producing neurons as if they were “foreign” bacteria or viruses and attack them.

Now, new research adds to the evidence that narcolepsy is an autoimmune condition. A team of scientists based in Denmark has discovered that CD8 T cells are also autoreactive in narcolepsy.

Birgitte Rahbek Kornum, an associate professor in the Department of Neuroscience at the University of Copenhagen, is the last and corresponding author of the study.

Studying immune cells in narcolepsy

Rahbek Kornum and colleagues analyzed blood samples from 20 study participants who had narcolepsy and 52 participants who did not have narcolepsy (the controls).

The scientists found autoreactive CD8 T cells in almost all of the people with narcolepsy. Interestingly, however, they also found the cells in a lot of the controls.

“We have found autoreactive cytotoxic CD8 T cells in the blood of narcolepsy patients,” reports Rahbek Kornum. “That is, the cells recognize the neurons that produce hypocretin, which regulates a person’s waking state.”

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