Some neurological benefits seen for Parkinson’s smokers in study
But patients still more likely to die of complications like cancer
People with Parkinson’s disease who smoke cigarettes are less likely to die of neurological problems than non-smokers, a new study shows — though Parkinson’s smokers were found to have a higher risk of death due to related smoking-related complications such as lung cancer.
The findings support the idea that some ingredients in cigarettes might have neuroprotective properties that could be explored in future research. But, the scientists stressed, the data suggest that the potential benefits of smoking cigarettes in Parkinson’s do not outweigh the substantial health risks of smoking.
“In our results, [Parkinson’s disease] smokers tended to have fewer deaths from neurologic causes but were significantly more likely to die from lung cancer,” the researchers wrote.
The study, “Association between smoking and all-cause mortality in Parkinson’s disease,” was published in npj Parkinson’s Disease.
Epidemiological studies have consistently shown that people who smoke cigarettes are less likely than non-smokers to develop Parkinson’s disease. Although the reasons for this association are not known, one possible explanation is that nicotine or other chemicals in cigarettes may offer protection against the neurodegenerative disease.
However, there has been little research into how smoking status affects outcomes like mortality for people who already have Parkinson’s. Further, most of the research that is available has focused on Western countries.
Now, a team of scientists in Korea analyzed the association between smoking and mortality outcomes for Parkinson’s patients using data collected by the Korean National Health Insurance Service.
“The objective of this study was to investigate the association between smoking status and all-cause mortality in [Parkinson’s disease] using a nationwide population-based cohort in Korea,” the team wrote.
The analysis included data for 1,535 people with Parkinson’s who were active smokers, 4,653 patients who were former smokers, and 21,880 patients who had never smoked. The active smokers tended to be younger than the other two groups, and more likely to be male.
Over an average follow-up period of more than five years, 8,663 deaths were recorded among these patients. The researchers constructed statistical models to compare mortality outcomes based on smoking status.
The results showed no significant difference in rates of all-cause mortality risk among the three groups. The intensity of smoking — how much patients smoked and for how long they had been smokers — also did not show a significant association with mortality risk.
“Compared with never-smokers, the risk of death in [Parkinson’s patients] was not significantly different between ex-smokers and current smokers,” the scientists wrote.
Further studies are warranted to determine the specific ingredients of cigarettes that are relevant to their neuroprotective effects.
The scientists also reviewed data from six earlier studies that assessed the relationship between smoking status and mortality for Parkinson’s patients in Western countries. The results were generally consistent with the finding that mortality risk is not significantly altered for patients who smoke cigarettes.
Closer inspection of the causes of death among the Korean patients indicated that death due to neurological problems was less common among smokers than never-smokers. However, smokers more commonly died from cancers, with smoking-related cancers like lung cancer being particularly common.
“To our knowledge, no study has compared the causes of death according to smoking status in patients with [Parkinson’s],” the researchers wrote.
“Based on our results, smoking seems to have a neuroprotective effect on [Parkinson’s] mortality; however, smoking itself causes smoking-related death; thus, overall, the association between smoking and mortality in [Parkinson’s] is nonsignificant,” the team wrote.
The researchers stressed that causes of death in chronic illnesses like Parkinson’s are often complicated, and this analysis of an insurance database did not include detailed clinical information.
Given the well-established risk of problems like cancer, the scientists said that “cigarette smoking, for its neuroprotective effect, is not recommended for individuals with” Parkinson’s.
However, they added that “further studies are warranted to determine the specific ingredients of cigarettes that are relevant to their neuroprotective effects.”
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