SAN DIEGO, CA – Amidst the mountain of evidence that smoking is harmful, there has been one bit of contrary evidence over the past few years. Studies have consistently found that smokers have lower rates of Parkinson's disease. However, the first explanation that comes to mind – that some ingredient in cigarettes helps prevent Parkinson's – may not be correct.
Researchers in the Netherlands have found evidence that higher consumption of coffee and alcohol is also associated with a lower incidence of Parkinson's. This, say the authors, suggests that smoking and other addictive behaviors may be a result of the same brain chemistry that helps prevent Parkinson's. Results of the study were presented at the American Academy of Neurology’s 52nd Annual Meeting in San Diego, CA, April 29 – May 6, 2000.
The theory investigated in this study suggests that smokers smoke because their brains have high levels of dopamine, a brain chemical implicated in so-called "novelty-seeking" behavior and addiction. People with lower levels of brain dopamine are not as likely to become addicted, but they may be more likely to develop Parkinson's disease, which results from drastic reductions in dopamine in the brain.
If this theory is correct, then intake of other addictive substances should also be associated with a reduced incidence of Parkinson's. This is what the Dutch team sought to prove with data from the large Rotterdam Study, an ongoing study of almost 8,000 subjects, aged 55 and older, who have been followed for up to ten years.
As with previous studies, this one found that cigarette smokers had lower levels of Parkinson's, by almost 50 percent, than did nonsmokers. "Moreover, there was a dose-effect relationship between the amount smoked over a lifetime and the risk of Parkinson's disease," said study author Patricia Willems-Giesbergen, MD, a researcher at the Erasmus Medical Center in Rotterdam. "The risk of Parkinson's decreased with an increase in the amount smoked."
As for coffee, people who drank high amounts had a lower incidence of Parkinson's. The beverage also had a dose-effect relationship with the disease whereby the risk for the disease rose as the amount of coffee consumed decreased. For alcohol, the researchers found that high consumption was related to a lower risk of Parkinson's. However, there was no dose-effect relationship noted.
The results support the hypothesis that patients predisposed to Parkinson's disease by their brain dopamine levels are more likely to restrict the use of addictive agents, said Willems-Giesbergen. But she cautions that the Rotterdam subjects need to be followed for a longer time to confirm the data.
The American Academy of Neurology, an association of more than 16,500 neurologists and neuroscience professionals, is dedicated to improving patient care through education and research.
For more information about the American Academy of Neurology, visit its Web site at http://www.aan.com. For online neurological health and wellness information, visit NeuroVista at http://www.aan.com/neurovista.
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