Archive for Wednesday, August 30, 2000

Narcolepsy cause theorized

August 30, 2000

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— A chemical that transmits signals in the brain -- discovered just two years ago -- may hold clues to the cause of the rare but dangerous disease narcolepsy.

Narcolepsy is marked by recurring episodes of daytime sleep in the victim, lasting from a few seconds to an hour. The disease can be merely inconvenient to some victims, but disabling and dangerous to others who may fall asleep while driving or operating machinery.

Stimulant drugs help some victims but can cause side effects. The cause of the disease has eluded researchers.

The discovery that a specific brain chemical is involved in narcolepsy could point the way for researchers to seek new treatments for the disease. There are about 125,000 narcolepsy patients in the United States. The disease usually strikes in the mid-teens to about age 25 and visits both sexes equally.

The two new studies are complimentary, "we both find that these cells are disappearing," Dr. Emmanuel Mignot of Stanford University said.

A team led by Mignot reports in the September issue of Nature Medicine that they found a lack of the chemical hypocretin in the brains of narcolepsy victims.

Hypocretins, which they noted were discovered just two years ago, are a type of neurotransmitter produced by the hypothamlus region of the brain. Prior studies have shown these signal transmitters to stimulate appetite and arousal.

"The finding that hypocretins are absent in most cases (of narcolepsy) ... strongly supports a central role for hypocretin deficiency in the human disorder," they reported.

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