Smoking Identified as an Independent Risk Factor for Dementia

Investigators examined the effect smoking has on the risk for dementia using a nationwide health claims database in Korea.

Smoking was associated with the development of dementia in a 2002-2013 cohort of 46,140 men in a population-based national health screening program, according to findings published in the Annals of Clinical and Translational Neurology.

Individual data from the Korean National Health Insurance System-National Health Screening Cohort were obtained. All participants in the cohort between 2002 and 2013 were age 60 years or older. Analysis of responses to a smoking habit questionnaire between 2002-2003 and 2004-2005 resulted in the categorization of individuals into 4 groups: continual smokers (n=12,672), short-term quitter of less than 4 years (n=4175), long-term quitter of 4 or more years (n=9268), and never smokers (n=20,025). From January 1, 2006, researchers followed participants for up to 8 years (mean, 7.11 years) to assess the development of Alzheimer disease, vascular dementia, and overall dementia.

Long-term quitters and never smokers had a decreased risk for overall dementia compared with continual smokers (hazard ratio [HR] 0.86; 95% CI, 0.75-0.99 for long-term quitters and HR 0.81; 95% CI, 0.71-0.91 for never smokers; Ptrend =.001). In addition, never smokers demonstrated a significantly reduced risk for Alzheimer disease compared with continual smokers (HR 0.82; 95% CI, 0.70-0.96; Ptrend =.010). Long-term quitters and never smokers also had a significantly decreased vascular dementia risk when compared with continual smokers (HR 0.68; 95% CI, 0.48-0.96 for long-term quitters and HR 0.71; 95% CI, 0.54-0.95 for never smokers; Ptrend =.017).

Limitations of the analysis included the primarily large Korean patient population and the restricted follow-up, which may not be sufficient to determine longer-term effects of smoking on neurophysiology.

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“Smokers should be encouraged to quit in order to reduce the risk of developing dementia,” the researchers concluded. “Smoking should be understood as a risk factor for dementia, especially in the elderly population as our study showed, and proper education regarding the benefit of smoking cessation should be done.”


Choi D, Choi S, Park SM. Effect of smoking cessation on the risk of dementia: a longitudinal study. Ann Clin Transl Neurol. 2018;5:1192-1199.