Its symptoms may include muscle weakness and paralysis, as well as impaired speaking, swallowing and breathing. In most cases it does not affect intellect, memory or the senses. Progress is relentless and generally rapid, with a life expectancy of between two and five years from the onset of symptoms. Once thought rare, it is in fact quite common. There are nearly 120,000 cases diagnosed worldwide each year.
Incidence is the number of new cases added in a defined period, usually a year.
Prevalence is the number of cases existing at any point in time. Research has found that the incidence is higher in people aged over 50 years. The disease affects each individual differently and can have a devastating impact on family, carers and friends. The rapidly progressive nature of the disease requires constant adaptation to increasing and changing levels of disability which, in turn, require increased levels of support. This page was last updated on 21st August 2001.