Study finds smoking may not be correlated with dementia

In prior studies, researchers have found a correlation between smoking and dementia. A new study from the University of Kentucky, however, has challenged that notion, suggesting that smoking may not be linked to a higher risk of dementia as previously thought.

“The underlying data (in those studies) was solid, but the analysis didn’t take into account the idea of competing risk of mortality, which we felt was an important factor to consider in this case since smoking is so strongly associated with earlier death,” said Erin Abner of the University of Kentucky’s Sanders-Brown Center on Aging (SBCoA).

“If, for example, we were studying cancer deaths and smoking, and one of the people in the study died from heart disease, what do we do with that person’s data? That person can’t possibly die from cancer since a competing event (death from heart disease) has occurred. If we ignore that information, the data are not telling the right story,” Abner added.

“In the case of our study, if smoking kills someone before they show signs of dementia, how can you accurately count that person? We think that those deaths should be accounted for when predicting dementia risk.”

As part of an SBCoA BRAiNS study, 531 initially cognitively healthy participants were probed for a period of 11 or more years in an effort to further understand how aging affects cognitive health. Researchers utilized Competing Risk Analysis, a statistical method, to find a potential link between smoking and dementia.

In the data, smoking was linked to an earlier risk of death. This was not the case for dementia, however. “To be clear, we are absolutely not promoting smoking in any way. We’re saying that smoking doesn’t appear to cause dementia in this population,” Abner stated.

“While our study results could influence smoking cessation policy and practice, we feel that the most important consequence of our work is to demonstrate how this method could change the way we approach dementia research and to advocate for its adoption in the appropriate areas of study.”

“However, the lack of neuropathological data, which is the gold-standard diagnosis for confirming correlations in a large population-based study, is a significant and ever-present barrier for dementia researchers.”

The findings were published in the Journal of Alzheimer’s Disease.