Tuesday, November 09, 2010

Hope for narcolepsy sufferers

The science of sleep: hope for narcolepsy sufferers | Life and style | The Guardian

Around 25,000 people in the UK 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 unproven – 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. "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 five-fold increase of the condition among genetically predisposed individuals who had suffered bacterial throat infections in childhood, while US 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, whose active ingredient, sodium oxybate, is a derivative of the illicit substance GHB. Licensed here since 2006, it works by mimicking the activity of hypocretin.

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