Science / Medicine : Brain Cell Activity Clue to Cause of Narcolepsy

California researchers have found a new clue to the cause of narcolepsy, a neurological disorder characterized by intense sleepiness and episodes of cataplexy--an abrupt loss of muscle tone that is often triggered by sudden strong emotions. They have found that cataplexy is caused by the same brain cells that cause loss of muscle tone during so-called “rapid-eye-movement,” or REM, sleep.

Narcolepsy affects an estimated one in 2,000 people in the United States, a total of more than 125,000. It also affects some animals, such as the Doberman pinschers used in the study conducted at UCLA, UC San Diego and Stanford University.

The researchers, headed by UCLA psychiatrist Jerome Siegel, embedded tiny wires in the dogs’ medial medulla--the area of the brain above the spinal cord--and measured electrical activity of cells during a normal waking state, normal sleep and cataplexy. They reported in the journal Science that a small group of cells that underwent frenzied electrical activity only during REM sleep and cataplexy.

The researchers’ next step will be to learn if those newly identified cells are normal cells being triggered at the wrong time to produce cataplexy or if they are abnormal themselves. A better understanding of the cells, they said, could lead to new treatments for narcolepsy.