Tobacco smoking and risk for dementia: evidence from the 10/66 population-based longitudinal study

Abstract

Objective: This study aimed to estimate the association between tobacco smoking and risk for dementia in seven low-and middle-income countries. Methods: Secondary analysis of the 10/66 population-based cohort study was conducted with 11,143 dementia-free individuals aged 65 years and older who were followed-up for an average of 3.8 years totalling 42,715 person-years. Cox regression with competing-risk analyses was used, controlling for age, gender, number of assets, past hazardous drinking, exercise and self-report of heart disease. Exposure was measured in packyears and smoking status. The number of packyears was calculated by multiplying the average number of packs per day by years of consumption up to 50 years old and up to age at baseline. Results: Meta-analysis of the results from each country yielded non-significant pooled relative risk ratios for all comparisons. There was no difference in risk for any dementia between 'ever smokers' compared to 'never smokers' (HR 0.96; 95% CI 0.82-1.13); 'current smokers' compared to 'never smokers' (HR 0.83; 95% CI 0.66-1.06); 'former smokers' compared to 'never smokers' (HR 1.06; 95% CI 0.88-1.27); 'current smokers' compared to 'former smokers' (HR 0.86; 95% CI 0.66-1.13). Results were similar for Alzheimer's disease (AD) and Vascular Dementia (VaD) as outcomes. Lifetime tobacco consumption (packyears) was not associated with any dementia (HR 1.00; 95% CI 0.99-1.00), nor with AD or VaD. Conclusion:Pooled results from all the countries showed no significant association between smoking and the onset of any dementia. Selective quitting in later-life might have biased the results towards no effect.

Risk Factors for Incident Dementia Among Older Cubans

“…In line with previous studies that attributed a large part of the dementia risk to lifestyle factors ( 9 ), lifestyle factors, particularly physical activity, dominate the risk profiles in this cohort of Cuban older adults. Previous studies using data from the wider Latin American 10/66 cohort including data from Dominican Republic, Mexico, Peru, Puerto Rico, Venezuela and Cuba ( 11 ), have demonstrated that better scores on a cardiovascular health index (based on physical activity, smoking, alcohol, hypertension, obesity, cholesterol, glucose, and intake of meat, fish, fruits and vegetables) was associated with lower risk of dementia ( 30 ). The current study adds that, when each factor is viewed independently, some but not all of these factors are associated with dementia and the associations differ for the younger and older age groups.…”

“…Moreover, the overall PAF was much higher in Latin America [55.8%, confidence interval [CI]: 54.9-56.7] than worldwide (35%, CI: 34.1-35.9), suggesting that health and lifestyle factors may contribute more to the dementia risk in Latin American countries than in other countries (9). Previous Latin American studies have shown associations between individual risk factors, such as tobacco use and APOE genotype, and dementia (10,11). In two studies in Mexico (12) and Argentina (13) risk profiles of cognitive impairment were examined, but a comprehensive analysis of factors associated with increased dementia risk is lacking.…”

Smoking and Neuropsychiatric Disease—Associations and Underlying Mechanisms

“…Moreover, never smoking was associated with lower risk of Alzheimer’s disease (HR 0.82, 95% CI 0.70–0.96) and long-term quitting (HR 0.68, 95% CI 0.48–0.96), and never smoking (HR 0.71, 95% CI 0.54–0.95) was associated with decreased risk of vascular dementia. In contrast, a meta-analysis including data from seven low- and middle-income countries (N = 11,143) indicated no increased risk of Alzheimer’s disease or vascular dementia when analyzing smoking status or cumulative smoking exposure (pack-years) [ 134 ].…”

Environmental Risk Factors for Early-Onset Alzheimer’s Dementia and Frontotemporal Dementia: A Case-Control Study in Northern Italy

“…Finally, our results seem to confirm that smoking, already found to be associated with dementia risk in some studies [66] and particularly in apolipoprotein E ε4 noncarriers [67], may be a risk factor for EOD. However, the relation between smoking and dementia has not been confirmed by some recent studies on overall dementia risk [68,69] and a meta-analysis on EOD based on three studies [70].…”