Researchers from the John Bevan MND Research Unit at Brunel University, Middlessex, have published two reports claiming there is a connection between the disease and alpha radiation, which results in higher incidence of the disease and people dying at a younger age.
The researchers looked at radon gas concentrations in England and Wales between 1981-89 and deaths from MND. They also studied patterns of disease in Japan following nuclear testing in the Pacific in the 1950s and 1960s. While radiation does not actually cause the disease, it acts as a trigger factor to accelerate it in the small percentage of the population who are already susceptible, the authors concluded.
Motor neurone disease, also known as amyotrophic lateral sclerosis or Lou Gehrig's disease, generally strikes in middle age. It affects nerves in the brain and spinal cord, and leads to the wasting of the muscles controlled by these nerves. Almost total paralysis follows.
It was first clinically reported in 1870, but there has been little progress since in therapy. The disease does not affect the brain itself, as has been demonstrated by the life of Professor Hawking, the Cambridge physicist and author, who has suffered from MND for about 25 years.
Overall, there are 3 deaths per 100,000 population in Britain which Dr Stuart Neilson, director of Medical Information Systems at the Brunel unit, says has risen 130 per cent since the 1960s when there were only 500 deaths per year. He says the "phenomenal increase" is due mainly to increased life expectancy with people living long enough to develop MND.
Those who die from MND tend to do so between the ages of 60 and 80, with the peak being at 70. But the British study found that those who lived in areas of high radon concentration tended to die on average two and a half years earlier.
Radiation exposure comes mainly from natural sources in Britain, with nearly half accounted for by radon gas. Only 13 per cent comes from artificial sources, of which 12 per cent comes from medical sources and 1 per cent from occupational exposure or industrial discharges.
Certain areas in Britain have particularly high areas of radon concentration - Cornwall, Devon, Northamptonshire and Somerset. In these areas MND mortality rate among men was much higher - 3.85 per 100,000 in Cornwall.
The results confirmed earlier work the researchers had done on MND mortality rates in Japan between the years 1950 and 1990.
Between the years of 1950 and 1963, until the Test Ban Treaty came into force, there were atmospheric weapons tests in the Pacific area.
In 1951, there was a mortality rate of 2.12 per 100,000 among the Japanese aged 55 or more. By 1963, this had jumped to a rate of 3.22 and among older men it even reached 4.5 per 100,000. The cessation of atom tests saw the rate drop swiftly to 2.39 per 100,000 in 1974.
Dr Neilson said he hoped the findings would lead to a greater understanding of the disease and what causes susceptibility to it.