A comprehensive review published in the January 1st issue of the journal SLEEP finds that, as with other diseases characterized by selective cell loss, narcolepsy may be caused by environmental exposures before the age of onset in genetically susceptible individuals - a possible contradiction to common belief that a person's body mass index, immune responses and stressful life events are factors that may cause narcolepsy.
Will Longstreth Jr., MD, MPH, and colleagues at the University of Washington identified and assessed studies previously conducted by other researchers on the epidemiology of narcolepsy.
According to Longstreth, the body mass index, immune responses and stressful life events of a person are most thoroughly examined in the search for etiologic risk factors, but noted that such associations may reflect a consequence rather than a cause of disease.
Although he and his colleagues have produced the scenario that environmental exposures may be a contributing factor into a person's development of narcolepsy, investigators must intensify the search for these exposures and focus on the first two decades of life, said Longstreth, adding that the identification of modifiable risk factors will help to prevent this disease.
Longstreth added that it is important to press on with further research into narcolepsy.
"The task of finding the etiology for narcolepsy will always depend on a partnership with the basic sciences, but epidemiologic studies can have an important role to play in elucidating how pathophysiologic mechanisms ultimately impact the public's health," said Longstreth.
Narcolepsy is a sleep disorder that causes people to fall asleep uncontrollably during the day. It also includes features of dreaming that occur while awake. Other common symptoms include sleep paralysis, hallucinations and cataplexy. About one out of every 2,000 people is known to have narcolepsy. There does seem to be a genetic link to it. Narcolepsy affects the same number of men and women.
Those who think they might have narcolepsy, or another sleep disorder, are advised to consult with their primary care doctor, who will refer them to a sleep specialist.