3 Causes of narcolepsy

Narcolepsy may be associated with damage to the amygdala. A cerebral proteinmyoglobin, showing coloured alpha helices. This protein was the first to have its structure solved by X-ray crystallography by Max Perutz and Sir John Cowdery Kendrew in 1958, which led to them receiving a Nobel Prize in Chemistry. A protein is a complex, has recently been discovered that is decreased in a large number or all narcolepsy patients. The proteinmyoglobin, showing coloured alpha helices. This protein was the first to have its structure solved by X-ray crystallography by Max Perutz and Sir John Cowdery Kendrew in 1958, which led to them receiving a Nobel Prize in Chemistry. A protein is a complex, involved is called hypocretin or orexinOrexin is the common name given to a pair of hormones discovered in rat brains by Masashi Yanagisawa at a Howard Hughes Medical Institute-funded lab at the University of Texas. Orexin has been found to have great importance in the study of appetite and sl. This might explain why narcolepsy runs in familiesA genetic disorder or genetic disease is a disease caused, at least in part, by the genes of the person with the disease. There are a number of possible causes for genetic defects: They may be caused by an unwelcome mutation, as are most cancers. There ar.

The neural control of normal sleep states and the relationship to narcolepsy are only partially understood. In humans, narcoleptic sleep is characterized by a tendency to go abruptly from a waking state to REM sleep with little or no intervening non-REM sleep. The changes in the motor and proprioceptive system s during REM sleep have been studied in both human and animal models. During normal REM sleep, spinal and brainstem alpha motor neuron hypopolarization produces almost complete atonia of skeletal muscleSkeletal muscle is a type of striated muscle, attached to the skeleton. Skeletal muscles are used to facilitate movement, by applying force to bones and joints; via contraction. They generally contract voluntarily (via nerve stimulation), although they cas via an inhibitory descending reticulospinal pathway. AcetylcholineThe chemical compound acetylcholine often abbreviated as ACh was the first neurotransmitter to be identified. It is a chemical transmitter in the central nervous system (CNS) as well as in the parasympathetic nervous system in many organisms including hum may be one of the neurotransmitterA neurotransmitter is a type of molecule that carries signals between neurons (nerve cells) at synapses in the nervous system. Neurotransmitters may be either excitatory ( EPSPs) or inhibitory ( IPSPs). That is, they may foster the initiation of a nerve is involved in this pathway. In narcolepsy, the reflex inhibition of the motor system seen in cataplexy is believed identical to that seen in normal REM sleep.

Despite the experimental evidence in human narcolepsy that there may be an inherited basis for at least some forms of narcolepsy, the mode of inheritance remains unknown.

4 Prevalence of narcolepsy

It is estimated that there are as many as 3 million people worldwide are affected by narcolepsy. In the United StatesThe United States of America also referred to as the United States U. America ¹ or the States is a federal republic in central North America, stretching from the Atlantic in the east to the Pacific Ocean in the west. It shares land borders with Canada in it is estimated that narcolepsy afflicts as many as 200,000 Americans, but fewer than 50,000 are diagnosed. It is as widespread as Parkinson's disease or multiple sclerosis and more prevalent than cystic fibrosis, but it is less well known. Narcolepsy is often mistaken for depression, epilepsy, or the side effects of medications.

Narcolepsy can occur in both men and women at any age, although its symptoms are usually first noticed in teenagers or young adults. There is strong evidence that narcolepsy may run in families; 8 to 12 percent of people with narcolepsy have a close relative with the disease.

Narcolepsy has its typical onset in adolescence and young adulthood. There is an average 15-year delay between onset and correct diagnosis, that may contribute substantially to the disabling features of the disorder. Cognitive, educational, occupational, and psychosocial problems associated with the excessive daytime sleepiness of narcolepsy have been documented. For these to occur in the crucial teen years when education, development of self-image, and development of occupational choice are taking place is especially damaging. While cognitive impairment does occur; it may only be a reflection of the excessive daytime somnolence.

The prevalence of narcolepsy in the United States has been estimated to be as high as one per 1,000. It is a major reason for patient visits to sleep disorder centers, and with its onset in adolescence, it is also a major cause of learning difficulty and absenteeism from school. Normal teenagers often already experience excessive daytime sleepiness because of a maturational increase in physiological sleep tendency accentuated by multiple educational and social pressures; this may be disabling with the addition of narcolepsy symptoms in susceptible teenagers. In clinical practice, the differentiation between narcolepsy and other conditions characterized by excessive somnolence may be difficult. Treatment options are currently limited. There is a paucity in the literature of controlled double-blind studies of possible effective drugs or other forms of therapy. Mechanisms of action of some of the few available therapeutic agents have been explored but detailed studies of mechanisms of action are needed before new classes of therapeutic agents can be developed.

Narcolepsy is much more common among men than among women. It is an underdiagnosed condition in the general population. This is partly because its severity varies from obvious down to barely noticeable. Some narcoleptics do not suffer from loss of muscle control. Others may only feel sleepy in the evenings.

5 Diagnosis

Diagnosis is relatively easy when all the symptoms of narcolepsy are present. But if the sleep attacks are isolated and cataplexy is mild or absent, diagnosis is more difficult.

Two tests that are commonly used in diagnosing narcolepsy are the polysomnogram and the multiple sleep latency test. These tests are usually performed by a sleep specialist. The polysomnogram involves continuous recording of sleep brain waves and a number of nerve and muscle functions during nighttime sleep. When tested, people with narcolepsy fall asleep rapidly, enter REM sleep early, and may awaken often during the night. The polysomnogram also helps to detect other possible sleep disorders that could cause daytime sleepiness.

For the multiple sleep latency test, a person is given a chance to sleep every 2 hours during normal wake times. Observations are made of the time taken to reach various stages of sleep. This test measures the degree of daytime sleepiness and also detects how soon REM sleep begins. Again, people with narcolepsy fall asleep rapidly and enter REM sleep early.

6 Treatment

Several treatments are available for narcolepsy. These treat the symptoms, not the underlying cause. The drowsiness is normally treated using stimulants such as methylphenidate ( Ritalin), amphetamine ( Adderall), methamphetamine ( Desoxyn) or Modafinil ( Provigil). However, in many cases, planned regular short naps can reduce the need for drowsiness treatment to a low or non-existent level. The loss of muscle control is treated using clomipramine, impramine, or protryptiline but this need only be done in severe cases.

In the US the approval of GHB (Xyrem) has added another drug to the armamentum available to physicians. It is thought to be effective because it increases the quality of nocturnal sleep.

Although there is no cure for narcolepsy, treatment options are available to help reduce the various symptoms. Treatment is individualized depending on the severity of the symptoms, and it may take weeks or months for an optimal regimen to be worked out. Complete control of sleepiness and cataplexy is rarely possible. Treatment is primarily by medications, but lifestyle changes are also important. The main treatment of excessive daytime sleepiness in narcolepsy is with a group of drugs called central nervous system stimulants. For cataplexy and other REM-sleep symptoms, antidepressant medications and other drugs that suppress REM sleep are prescribed. Caffeine and over-the-counter drugs have not been shown to be effective and are not recommended.

In addition to drug therapy, an important part of treatment is scheduling short naps (10 to 15 minutes) two to three times per day to help control excessive daytime sleepiness and help the person stay as alert as possible. Daytime naps are not a replacement for nighttime sleep.

Ongoing communication among the physician, the person with narcolepsy, and family members about the response to treatment is necessary to achieve and maintain the best control.

7 Research

Studies supported by the National Institutes of Health (NIH) are trying to increase understanding of what causes narcolepsy and improve physicians' ability to detect and treat the disease. Scientists are studying narcolepsy patients and families, looking for clues to the causes, course, and effective treatment of this sleep disorder.

Recent discovery of families of dogs that are naturally afflicted with narcolepsy has been of great help in these studies. Some of the specific questions being addressed in NIH-supported studies are the nature of genetic and environmental factors that might combine to cause narcolepsy and the immunological, biochemical, physiological, and neuromuscular disturbances associated with narcolepsy.

Scientists are also working to better understand sleep mechanisms and the physical and psychological effects of sleep deprivation and to develop better ways of measuring sleepiness and cataplexy.

Examples of areas of potential research include studies on the pathophysiology of narcolepsy; abnormalities of circadian rhythms, particularly anatomical and biochemical substrates; the molecular genetics of narcolepsy; and the development of new therapies. New, more sensitive, and specific objective diagnostic procedures need to be developed and validated.

While studies in the naturally occurring narcoleptic dog model suggest an autosomal recessive mode of transmission in that model, genetic analysis of cohorts of narcoleptic patients and identification of informative families are needed to define the mode of inheritance and to facilitate the search for gene markers.

8 Coping with narcolepsy

Learning as much about narcolepsy as possible and finding a support system can help patients and families deal with the practical and emotional effects of the disease, possible occupational limitations, and situations that might cause injury. A variety of educational and other materials are available from sleep medicine or narcolepsy organizations.

Support groups exist to help persons with narcolepsy and their families.

Individuals with narcolepsy, their families, friends, and potential employers should know that:

• Narcolepsy is a life-long condition that requires continuous medication.
• Although there is not a cure for narcolepsy at present, several medications can help reduce its symptoms.
• People with narcolepsy can lead productive lives if they are provided with proper medical care.
• If possible, individuals with narcolepsy should avoid jobs that require driving long distances or handling hazardous equipment or that require alertness for lengthy periods.
• Parents, teachers, spouses, and employers should be aware of the symptoms of narcolepsy. This will help them avoid the mistake of confusing the person's behavior with laziness, hostility, rejection, or lack of interest and motivation. It will also help them provide essential support and cooperation.
• Employers can promote better working opportunities for individuals with narcolepsy by permitting special work schedules and nap breaks.

9 See also

• Dyssomnia
• Orexin

10 External links

• http://www.websciences.org/narnet/default.html
• http://www.narcolepsy.org.uk/index_html

Sleep disorders

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