Rigidity, tremors, slowness, along with difficulties walking and talking, are well-known signs of Parkinson’s disease (PD). However for individuals with PR, a less publicized, but often more sinister condition is the severe sleep disorder narcolepsy.

Narcolepsy is a sleep disorder characterized by sudden and uncontrollable episodes of deep sleep, severe fatigue and general sleep disorder.

New research reveals severe damage to the same small group of neurons for both conditions giving scientists hope that a different treatment approach may resolve the sleep symptoms.

In their report in the June issue of the journal Brain UCLA researchers 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 muscle tone without loss of consciousness; that is, although the person cannot talk or move, they are otherwise in a state of high alertness, feeling, hearing and remembering everything that is going on around them.

“When we think of Parkinson’s, the first thing that comes to mind are the motor disorders associated with it,” said Jerry Siegel, lead researcher.

“But sleep disruption is a major problem in Parkinson’s, often more disturbing than its motor symptoms. And most Parkinson’s patients have daytime sleep attacks that resemble narcoleptic sleep attacks.”

In fact, said Siegel, Parkinson’s disease is often preceded and accompanied by daytime sleep attacks, nocturnal insomnia, REM sleep disorder, hallucinations and depression. All of these symptoms are also present in narcolepsy.

Source: UCLA