Association of Changes in Smoking Intensity With Risk of Dementia in Korea

Abstract

ImportanceSeveral observational studies have reported that smoking cessation is associated with a lower risk of dementia. However, no studies have examined the association between change in smoking intensity and risk of dementia.ObjectiveTo investigate the association between a change in smoking intensity, including smoking reduction and smoking cessation, and risk of all dementia.Design, Setting, and ParticipantsThis cohort study used data from the National Health Insurance Service database of Korea. The cohort included participants 40 years or older who underwent biennial health examinations (2009 and 2011) and had current smoking status at the first health examination. The cohort was followed up until December 31, 2018, and statistical analysis was performed between July and December 2021.ExposuresChange in smoking intensity from baseline was defined operationally as follows: quitters (stopped smoking), reducers I (decreased number of cigarettes smoked per day by ≥50%), reducers II (decreased 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%).Main Outcomes and MeasuresThe primary outcome was newly diagnosed dementia, which was identified by prescribed antidementia medications with concomitant International Statistical Classification of Diseases and Related Health Problems, Tenth Revision diagnosis codes for dementia. Adjusted hazard ratios and 95% CIs were used to determine the association between change in smoking intensity and incidence of dementia, including Alzheimer disease (AD) and vascular dementia (VaD).ResultsA total of 789 532 participants (756 469 males [95.8%]; mean [SD] age, 52.2 [8.5] years) were included. During a median (IQR) follow-up period of 6.3 (6.1-6.6) years, 11 912 dementia events, including 8800 AD and 1889 VaD events, were identified. Overall, participants in the quitter group had a significantly lower risk of all dementia (adjusted hazard ratio [aHR], 0.92; 95% CI, 0.87-0.97) compared with those in the sustainer group. Those in the reducer I (aHR, 1.25; 95% CI, 1.18-1.33) and increaser (aHR, 1.12; 95% CI, 1.06-1.18) groups had a significantly higher risk of all dementia compared with those in the sustainer group.The patterns for AD and VaD remained consistent with patterns for all dementia.Conclusions and RelevanceThe results of this study showed that smoking cessation was associated with a lower risk of dementia compared with sustained smoking intensity, while smoking reduction was associated with a higher risk. Smoking cessation should be emphasized in efforts to reduce the disease burden of dementia.

Lower risk of depression after smoking cessation and alcohol abstinence in patients with gastric cancer who underwent gastrectomy: A population‐based, nationwide cohort study

“…Multiple imputation was also used to account for missing covariate data (i.e., those who reported all three lifestyle behaviors but lacked data in one or more variables in the health examination results). 32,33 Two-sided p values < .05 were considered statistically significant. All statistical analyses were performed using SAS version 9.4 (SAS Institute Inc.).…”

“…To evaluate the association between lifestyle behaviors and depression development, we performed a multivariable Cox proportional hazard regression analysis using three models: (1) model 1, nonadjusted; (2) model 2, adjusted for age and sex; and (3) model 3, adjusted for age, sex, smoking status on the index date (nonsmoker, former smoker, and current smoker), drinking status on the index date (nondrinker, mild drinker, and heavy drinker), regular physical activity on the index date, and the presence of diabetes mellitus, hypertension, dyslipidemia, chronic kidney disease, cardiovascular disease, heart failure, COPD, cerebrovascular disease, liver disease, and obesity. Multiple imputation was also used to account for missing covariate data (i.e., those who reported all three lifestyle behaviors but lacked data in one or more variables in the health examination results) 32,33 . Two‐sided p values < .05 were considered statistically significant.…”

“…[1][2][3][4][5][6] It is well known that patients who have cancer have a higher risk of depression ranging from 4% to 58%: up to five times higher than the general population. 1,[6][7][8][9] The overall prevalence of psychological distress among patients with gastric cancer and those with gastric cancer who undergo surgery has been reported to be as high as 33.5%-57%. [10][11][12] With the increasing survival rate of patients with gastric cancer, 13 the importance of maintaining a long-term healthy lifestyle is rising.…”

Risk of depression and anxiety in multiple sclerosis and neuromyelitis optica spectrum disorder: A nationwide cohort study in South Korea

“…Patients diagnosed with depression or anxiety during the follow-up period were identified by one or more hospitalization or at least two outpatient clinic visits for the ICD-10 codes (F32–33 for newly diagnosed depression and F40–F41 for newly diagnosed anxiety, respectively), as in previous studies. 24,25 The prescription data for the definition of depression/anxiety were not available due to the limited access to the KNHIS. The study cohort was followed from 1 year after the year of first diagnosis (for pwMS or pwNMOSD) or the matched index year (for controls) until the year of the first diagnosis of depression or anxiety or the end of the study period (31 December 2019), whichever came first.…”

Errors in the Byline and Figure

“…The missing lines for the 95% CIs have also been added to the first panel. This article has been corrected …”