Narcolepsy Link To Cell Damage

Neuroscientists are reporting that the incurable sleep disorder known as narcolepsy is caused by damage to nerve cells in the brain that creates sleepiness by day and broken slumber at night.

Narcolepsy stems from the breakdown of nerve fibers called axons in the forebrain, a region active in inducing sleep, and the amygdala, which is responsible for emotion.

Dr. Jerome Siegel, head of neurobiology research at the Sepulveda Veterans Affairs Medical Center in Los Angeles, observed degeneration of axons and amygdala in narcoleptic dogs just before they begin to show symptoms.

"This is the first evidence of degeneration in narcolepsy," he said.

The nerve fibers break up into little beads that Siegel described as looking like a string of pearls. Although he hasn't observed cell death, he suspects there may be a small amount involved.

Researchers still don't why those fibers begin to break down, according to presentations at a meeting of the Society for Neuroscience. With a breakdown in the communication between nerve cells, the cells that survive "may end up wired wrong," Siegel said.

The illness affects an estimated 250,000 people in the United States, but only 50,000 have been diagnosed, according to Dr. Robert McCarley of Harvard Medical School and the Brockton Veterans Affairs Medical Center in Massachusetts.
McCarley suggested that the disorder is probably as common as multiple sclerosis. While not fatal, it can lead to accidents at work or while driving.

Narcolepsy sufferers walk around feeling as sleepy as someone who has been awake for 48 hours. They are afflicted by cataplexy, a loss of muscle tone triggered in response to emotional excitement. They have sleep paralysis, which makes them unable to move when falling asleep or waking up, and experience visual or auditory hallucinations as they drift off.

Written by Jane E. Allen