Narcolepsy discovered causes of enigmatic sleeping sickness

Research team identifies the triggers of rare sleeping sickness

In the rare sleeping sickness narcolepsy sufferers have pronounced daytime sleepiness and are prone to falling asleep. The chronic disease was documented as early as 1877, but until today the causes of the disease have been a mystery. Now a Swiss study brought light into the darkness. Researchers were able to decipher the triggers of narcolepsy.

Sudden sleep attacks, disturbed night sleep, hallucinations, loss of muscle control - narcolepsy is a severe cut in the quality of life for sufferers. The sudden fall asleep is additionally associated with accident hazards. Patients with chronic sleeping sickness did not know why they have this disease. A Swiss research team with the participation of the University Sleep-Wake-Epilepsy-Center Bern (SWEZ) now found the causes of rare narcolepsy. Their study results were recently published in the renowned journal "Nature".

Spontaneous falling asleep is a typical symptom of narcolepsy, a rare chronic sleeping sickness. In addition to insomnia sufferers also suffer from muscle control loss, constant fatigue and hallucinations. Researchers now found new causes of the disease. (Image: katie_martynova / fotolia.com)

Narcolepsy - a rare and puzzling condition

Only about 0.05 percent of the population suffers from chronic sleeping sickness, the researchers report. The underlying mechanisms have remained largely a mystery since the discovery of the disease. The team led by Professor Federica Sallusto at the Institute for Research in Biomedicine in Bellinzona (IRB) and Professor Claudio LA Bassetti from the Sleep-wake-epilepsy Center (SWEZ) of the University Department of Neurology at the Inselspital in Bern made the breakthrough, identified the triggers and now offers new possibilities for diagnosis and therapy.

What was already known

Previous research has already shown that narcolepsy is caused by the steady loss of a protein in the brain. According to the Swiss research group, the decrease in the protein hypocretin is genetic and usually occurs in certain individuals who have a genetic susceptibility to it. Why it comes to the continuous loss of the protein was previously considered insufficiently understood.

Immune reactions trigger sleeping sickness

The Swiss researchers showed for the first time in their study that immune reactions are responsible for the loss of the protein hypocretin. The team identified so-called autoreactive T-lymphocytes, which induce an immune response that causes the loss. Lymphocytes belong to the white blood cells and are natural components of the blood. Their tasks include the detection and destruction of foreign substances such as viruses and bacteria. In narcolepsy patients, the autoreactive T lymphocytes destroy certain neurons in the brain that are responsible for the production of hypocretin.

New therapy option

"Using sensitive methods, we were able to identify autoreactive T cells as causative agents of this disease," summarizes Professor Federica Sallusto in a press release from the University Hospital in Bern. These lymphocytes could cause inflammation that leads to neuronal damage or even destroys hypocretin-producing neurons. "If we block autoreactive T cells in the early stages, we may be able to limit neuronal loss and prevent the disease from progressing," explains Sallusto.

Narcolepsy is often recognized too late

"This study will raise awareness of narcolepsy, which is poorly understood among the general population and often diagnosed late or late by doctors," added Professor Claudio Bassetti. The new findings would open up new opportunities for early diagnosis as well as new treatment approaches.

What is the role of the hypocretin protein?

As previously mentioned, loss of hypokretin leads to the typical symptoms of sleeping sickness such as chronic fatigue, sleep disorders, sleep attacks, impaired consciousness and muscle control losses. The hypocretin protein is produced in the hypothalamic brain region and regulates sleep-wake behavior as well as emotional and nutritional behavior. 95 percent of narcolepsy patients have a specific genetic marker (HLA allele DQB1 * 0602). For this reason, doctors assume that it is an autoimmune disease.

Narcolepsy often occurs after infectious diseases

As the researchers report, narcolepsy often occurs as a result of infectious diseases such as influenza. This points to a possible role of environmental factors as triggers of the autoimmune process. However, the exact mechanisms why T lymphocytes attack neurons in the brain remain unclear. (Vb)