Korea: A study published in JAMA Network Open has concluded that smoking cessation is essential to reduce the risk of all dementia, including Alzheimer's disease (AD) and vascular dementia (VaD). The researchers also said that smoking reductions increased the risk of dementia. It is important to emphasize more on smoking cessation and not to smoke reduction.
It is already known that smoking cessation lowers the risk of dementia. There needs to be more data on the association between changes in smoking intensity (cessation and reduction) and dementia risk.

Jeong et al. and colleagues from Seoul National University College of Medicine did a study to investigate this association.
Exposures Change in smoking intensity from baseline was quitters (stopped smoking), reducers I (decreased number of cigarettes smoked per day by ≥50%), reducers II (reduced number of cigarettes smoked per day by 20%-50%), sustainers (maintained [decreased or increased] number of cigarettes smoked per day by less than 20%), or increasers (increased number of cigarettes smoked per day by ≥20%).
The study summary includes the following:
The data was used from the National Health Insurance Service database of Korea.
The participants were 40 or older and underwent biennial health examinations (2009 and 2011).
The study participants had current smoking status at the first health examination.
There were 789 532 participants, with 95.8% male and of mean age of 52.2 years.
The median follow-up period of 6.3 years.
Total 11 912 dementia events occurred, including 8800 events of Alzheimer's disease (AD) and 1889 events of Vascular Dementia.
In the quitter group, there was a lower risk of all dementia with an adjusted hazard ratio of 0.92 than in the sustainer group.
The participants in the reducer I had aHR of 1.25, and increaser with aHR of 1.12 had a higher risk of all dementia than those in the sustainer group.
The patterns for AD and VaD remained consistent with patterns for all dementia.
In this study, the primary outcome was newly diagnosed dementia identified by prescription antidementia medications with concomitant International Statistical Classification of Diseases and Related Health Problems, Tenth Revision diagnosis codes for dementia.
The researchers highlighted that smoking cessation could reduce the disease burden of dementia.
Further reading:
Jeong S, Park J, Han K, et al. Association of Changes in Smoking Intensity With Risk of Dementia in Korea. JAMA Netw Open. 2023;6(1):e2251506. doi:10.1001/jamanetworkopen.2022.51506