What is motor neuron disease?
Motor neuron disease (MND), also known as amyotrophic lateral sclerosis (ALS), affects movement by attacking the nerves connecting the spinal cord to the muscles. It can strike anyone at any age. The early symptoms are slurred speech and stumbling. As the nerves gradually waste away, people with the condition eventually lose all control over their voluntary movements, even processes like swallowing and eye movements, although it never affects mental ability.
Do we understand MND?
The causes of motor neuron disease remain unknown. Some scientists think a slow-acting virus may be involved while others think that toxins may be to blame. In 10% of cases, the cause has been linked to an altered gene inherited from an affected parent – familial motor neuron disease. There is no cure for the condition at present. Researchers are investigating ways of replacing the lost motor neurons.
What happened on Guam?
In the 1940s and 1950s, the incidence of motor neuron disease on the western Pacific island of Guam was much higher than elsewhere in the world. The disease did not seem to be inherited or contagious – no virus could be found. A possible explanation was the islander's habit of using cycad seeds to make flour. These are poisonous if not washed properly.