A research team from Switzerland with the collaboration of Dr. Ing. Ulf Kallweit of the University of Witten / Herdecke (UW / H) has identified the cause of chronic narcolepsy. The results of this study have recently been published in the renowned journal Nature.
Narcolepsy is a rare neurological disorder affecting about 40,000 people in Germany. The first symptoms often occur during adolescence or young adulthood, but even young children can already be affected. The main symptoms of the disease are chronic and severe daytime sleepiness, falling asleep and cataplectic attacks, i.e. a sudden sudden loss of muscle tension caused by emotions.
In addition, neuropsychiatric, motoric and metabolic disorders can occur. Narcolepsy is associated with a severe reduction in performance and quality of life.
So far it still takes more than ten years from the appearance of the first symptoms to the diagnosis on average. The diagnosis is usually made by history, sleep laboratory research and a nerve water examination, in which the so-called hypocretin value is investigated.
Narcolepsy is caused by a gradual loss of nerve cells in the so-called hypothalamus (a specific area in the brain) that produce hypocretin. Hypocretin is a neuropeptide that is essential for maintaining sleep and vigilance, but is also relevant for emotion, nutrition and reward behavior. To date, it has been known that both a specific genetic predisposition, the presence of the so-called HLA allele DQB1 * 0602 haplotype and environmental factors such as certain infections or individual vaccines must be present. The mechanism that led to the destruction of the neurons was previously unknown.
In the current study the research group used an innovative, advanced and particularly sensitive method to study the repertoire of T-cells in the blood of people with narcolepsy. Thus, for the first time CD4 (and in some cases CD8 subtypes) T lymphocytes have been identified that respond to hypocretin and another protein ("TRIB2") that is expressed in hypocretin neurons. These T cells can cause inflammation, thereby destroying neurons, or they can potentially directly destroy the neurons in which hypocretin is produced.
The treatment of narcolepsy is purely symptomatic, a cure is not yet possible. In addition to behavioral measures such as planning a daily structure in which sleeping periods are planned during the day, drug treatment is primarily focused on the main symptoms of the disease. Daytime sleepiness can be treated by different stimulants or growth-enhancing drugs, and other drugs can alleviate cataplexy.
The co-lead author of the study and research group leader for clinical sleep and neuroimmunology at the Institute of Immunology or UW / H, Dr. ir. med. Ulf Kallweit, the possible consequences for clinical practice, were particularly important in research. He emphasizes that this study could help diagnose narcolepsy more easily and quickly in the future by means of a blood test for autoreactive T lymphocytes compared to hypocretin. This would also help to start treatment earlier, for example to successfully complete the school or to study. Sleep specialist Dr. Kallweit also emphasizes the importance of the study for new treatment options.
The loss of hypocretin-producing neurons in narcolepsy is slowly progressive and presumably irreversible. If we know the exact cause, the autoreactive T cells can now be able to suppress these cells at the onset of the disease, slowing down or even stopping further cell death. The severity of narcolepsy or even the progression of the disease can be affected. Kallweit: "In a next step, suitable therapies must now be developed."
Since its founding in 1982, the University of Witten / Herdecke (UW / H) has played a pioneering role in the German educational landscape. As a model university with about 2,500 students in the field of health, economics and culture, UW / H is reforming the classic alma mater. Knowledge transfer at UW / H always goes hand in hand with value orientation and personality development.
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More information: Dr. med. Ulf Kallweit, Clinical Sleep and Neuroimmunology, Institute of Immunology, University of Witten / Herdecke