Parkinson's disease is well-known for its progression of motor disorders: stiffness, slowness, tremors, difficulties walking and talking. Less well known is that Parkinson's shares other symptoms with narcolepsy, a sleep disorder characterized by sudden and uncontrollable episodes of deep sleep, severe fatigue and general sleep disorder.

Now a team of UCLA and Veterans Affairs researchers think they know why the two disorders share something in common: Parkinson's disease patients have severe damage to the same small group of neurons whose loss causes narcolepsy. The findings suggest a different clinical course of treatment for people suffering with Parkinson's that may ameliorate their sleep symptoms.

In their report in the June issue of the journal Brain and currently online, Jerry Siegel, professor of psychiatry and biobehavioral sciences at the Semel Institute for Neuroscience and Human Behavior at UCLA, assistant resident neurobiologist Thomas C. Thannickal and associate research physiologist Yuan-Yang Lai have determined that Parkinson's disease patients have a loss of up to 60 percent of brain cells containing the peptide hypocretin. In 2000, this same group of UCLA researchers first identified the cause of narcolepsy as a loss of hypocretin, thought to be important in regulating the sleep cycle. This latest research points to a common cause for the sleep disorders associated with these two diseases and suggests that treatment of Parkinson's disease patients with hypocretin or hypocretin analogs may reverse these symptoms.

More than 1 million people in the U.S. have been diagnosed with Parkinson's disease, and approximately 20 million worldwide. (The percentage of those afflicted increases with age.) Narcolepsy affects approximately one in 2,000 individuals about 150,000 in the United States and 3 million worldwide. Its main symptoms are sleep attacks, nighttime sleeplessness and cataplexy, the sudden loss of skeletal muscl
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Contact: Mark Wheeler
mwheeler@mednet.ucla.edu
310-794-2265
University of California - Los Angeles
11-May-2007