Smoking a new factor in sclerosis

Smoking may be associated with an increased risk of motor neurone disease, research suggests.

Scientists came to the conclusion after analysing data from five long-term studies involving more than one million participants.

They found that compared to non-smokers people who smoke have a 42 per cent higher risk of developing amylotrophic lateral sclerosis (ALS), a form of motor neurone disease.

Former smokers had an even greater increased risk of 44 per cent.

The chances also increased with heavier levels of smoking. For every ten extra cigarettes smoked a day, the chances of developing ALS rose by 10 per cent, while every ten years of smoking increased the risk by 9 per cent.

ALS risk also went up as the age that people took up smoking dropped.

There is no cure for the fatal disease which causes progressive degeneration of the nerves that control voluntary muscle movement, weakness and wasting.

Celebrity physicist Professor Stephen Hawking is one of the best-known sufferers of the condition.

The new research, led by Dr Hao Wang appears in the journal Archives of Neurology.