UCLA Researchers Claim To Have Found The Cause of Narcolepsy
In 2000, researchers at the UCLA Center for Sleep Research published a study showing that people suffering from narcolepsy had 90 percent fewer neurons containing the neuropeptide hypocretin in their brains than normal people. It was the first sign that narcolepsy, a disorder characterized by the inability to control when you fall asleep, may have a biological basis.
The researchers also showed that hypocretins acted as arousing chemicals that keep us awake and keep our moods up. The researchers took this to mean that dying hypocretin cells were the cause of narcolepsy, but it appears that another brain cell is at least playing a part in causing the disorder.
The same UCLA team that initially reported that too few hypocretins is the source of the sleep disorder has published a new study in the Annals of Neurology claiming that histomines, immune system chemicals that kill invading cells, may also be contributing to narcolepsy.
Medical Daily reported that the researchers examined the brains of five narcoleptic patients and seven normal brains, all from human cadavers. They showed that all five narcoleptic brains were also showed signs of cataplexy, a disorder that normally accompanies narcolepsy in which the body loses all muscle function and causes patients to collapse if standing. The brains also had an average of 64 percent more histamine neurons than the normal brains.
“Our current findings indicate that the increase of histamine cells that we see in human narcolepsy may cause the loss of hypocretin cells,” explained Jerome Siegel, director of the Center for Sleep Research at the UCLA Semel Institute for Neuroscience and Human Behavior.
Interestingly, animals with narcolepsy do not show the same increased levels of histomine neurons, but Siegel says that may be explained by the different way hypocretins are inhibited in animal bodies. “We know that narcolepsy in the animal models is caused by engineered genetic changes that block hypocretin function. However, in humans, we did not know why the hypocretin cells die.”