Smokers, so often the target of health warnings concerning the negative consequences of tobacco use, can now point to one potential benefit of their nicotine addiction.
According to a study published this morning in the US medical journal Archives of Neurology, cigarette smoking is associated with a reduced risk of developing Parkinson's disease. Researchers at the University of California School of Public Health in Los Angeles found that long-term smokers and those currently smoking had the lowest risk of developing the disease.
Parkinson's disease is a progressive disorder of the nervous system characterised by tremor, a slowness of voluntary movement and increased muscle tone. It affects about one in 100 people over the age of 65 and most commonly occurs between the ages of 50 and 79.
In Parkinson's disease, nerve cells in one part of the brain degenerate, reducing the production of the neurotransmitter, dopamine, and leading to slow, reduced movements (bradykinesia) and tremor.
Dr Beate Ritz and colleagues conducted the first ever pooled analysis of data from 12,000 people included in 11 Parkinson's studies to see if smoking had a protective effect. They found that current smokers had the lowest risk of developing Parkinson's disease, while the reduction in risk lessened the longer a person had quit smoking. But they found a small decrease in risk in those who had smoked up to 25 years prior to a diagnosis of Parkinson's disease.
While the researchers found no association between smoking and Parkinson's disease risk in people over 75, the protective effect of smoking was the same in men and women. And other tobacco products also appeared to be protective with men who smoked pipes or cigars having a 54 per cent lower risk of developing Parkinson's disease.
"The biochemical basis for possible preventive effects of smoking or of a substitute delivered through cigarette smoke is not well understood," the authors say. Possible mechanisms include a protective effect of chemicals in tobacco products or a reduction in the production of toxins in people who smoke.
However, the health risks of smoking far outweigh any potential benefit.
For advice on smoking cessation contact the Irish Cancer Society's Quitline at 1850 201203