Hope for narcolepsy sufferers

Claire Allen once laughed so much at a friend’s joke, she fell down in the middle of a road.

Another time, she attempted to jump out and surprise someone, but was so tickled by her plan that she collapsed before even reaching her hiding place.

If the 35-year-old scientist, whose case was highlighted in newspaper reports recently, was not on medication, she could drop off 100 times a day.
Allen suffers from cataplexy—a disorder associated with narcolepsy—in which muscle-tone loss is triggered by amusement or surprise.

About 25 000 people in the United Kingdom have narcolepsy, a condition characterised by sudden and uncontrollable episodes of deep sleep, often at times of stress or even sexual arousal. There’s no known cure, but in terms of medical advances, 2010 has been lively.

As well as the reported alleged links to the swine flu vaccine in August—still unproved—Swiss researchers claimed in February to have identified the overproduction of an antibody, Trib2, in the immune systems of narcoleptics. Scientists at Geneva and Lausanne universities believe Trib2 is responsible for destroying hypocretin-secreting neurons in the brain.

Hypocretin is a hormone that regulates sleep, so low levels interfere with non-REM (rapid eye movement) sleep and makes staying awake for long periods a struggle.

Excitingly, the tests suggested this damage could potentially be stabilised with intravenous immunoglobulin, a laboratory-made antibody. If patients could be diagnosed and treated within a year of symptoms presenting—when the antibodies are at their most destructive levels—the illness’s impact could be greatly reduced.

Early diagnosis is critical
“There is a chance to save some of the hypocretin cells at early onset,” says Professor Adrian Williams, who runs the sleep disorders centre at St Thomas’s Hospital, London, and this year became the UK’s first chair in sleep medicine.

“Unfortunately, narcolepsy is still under-recognised and it is typically a few years between onset of symptoms—usually in the teens—and diagnosis.” Other studies indicate environmental factors that could “switch on” the gene for narcolepsy, which exists in a third of the population.

In June a Journal of Sleep Research paper reported a fivefold increase of the condition among genetically predisposed individuals who had suffered bacterial throat infections in childhood, whereas American studies suggested that exposure to heavy metals and gardening chemicals, as well as passive smoking, could be a trigger.

Perhaps the most significant development of recent years has been a medicine, Xyrem, the active ingredient of which, sodium oxybate, is a derivative of the illicit substance GHB. Licensed in Britain since 2006, it works by mimicking the activity of hypocretin.

Gareth Tims, a 33-year-old accountancy graduate from Worcester, central England, was one of the first British patients to test it. Prone to disturbed night-time sleep, he’d wake more than 30 times in six hours.

Tims found the results “miraculous”. He now mostly wakes refreshed from a seven-hour sleep. But he is among the lucky few. Despite its 70% success rate, use in the United States as first-line treatment and lack of side effects, Xyrem is only available to one in 100 UK sufferers.

“It’s the drug of choice, finally allowing narcoleptics to live a normal life, yet the link to GHB means it is tightly controlled, and remains under patent,” says John Cherry, director of Narcolepsy UK. And it’s not cheap—a year’s supply sets the UK health service back £14 000.

Cherry is hopeful that publicising individuals’ experiences, coupled with the new findings, will lead to change, yet emphasises that the disorder remains underfunded because “it can ruin your life, but it can’t kill you”.—