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Up to 40% of all dementia cases may be preventable, primarily by treating or acting on well-established cardiovascular risk factors such as diabetes, hypertension, smoking, and physical inactivity. Whether physical inactivity is associated with risk of non-Alzheimer's dementia – a disease influenced by cardiovascular risk factors – and whether a given association differs for physical activity in leisure time and at work remains unknown. We conducted a prospective cohort study including 117,616 individuals from the Copenhagen General Population Study and the Copenhagen City Heart Study with up to 43 years of follow-up. Multifactorially adjusted hazard ratios for low versus high physical activity at leisure time was 1.60 (95% confidence interval 1.40–1.83) for non-Alzheimer's dementia and 0.94 (0.80–1.11) for Alzheimer's disease. Corresponding values for non-Alzheimer's dementia after additional adjustment for physical activity at work or apolipoprotein E (APOE) genotype were 1.60 (1.40–1.83) and 1.82 (1.34–2.15). Multifactorially and APOE adjusted hazard ratios for high versus low physical activity at work were 1.50 (1.10–2.05) for non-Alzheimer's dementia and 1.62 (1.14–2.31) for Alzheimer's disease. When combining the two types of physical activity, physical activity in leisure time had the strongest relationship with risk of non-Alzheimer's dementia. Physical inactivity in leisure time was associated with increased risk of non-Alzheimer's dementia, independent of modifiable risk factors and physical activity at work. The present study thus provides evidence for public health advice on physical activity in leisure time for the vascular part of dementia. [Display omitted] • Prospective study including 117,616 individuals from the general Danish population. • Up to 43 years of follow-up with no losses to follow-up. • Low leisure physical activity associates with high risk of non-Alzheimer's dementia. • Leisure versus work physical activity is superior in predicting risk. • Public health advice on physical activity may prevent non-Alzheimer's dementia. [ABSTRACT FROM AUTHOR]

Studies of self-reported coffee consumption and smoking on risk of dementia have shown results conflicting with two-sample Mendelian randomization studies. We tested the hypotheses that coffee consumption and smoking influence risk of dementia using observational and one-sample Mendelian randomization designs with individual level data. We included 114,551 individuals from two Danish general population cohorts (median age 58 years). First, we tested whether high self-reported coffee consumption/smoking were associated with risk of dementia. Second, whether genetically predicted high coffee consumption/smoking due to variation near CYP1A1/AHR/CHRNA3 genes were associated with risk of dementia. We observed 3,784 dementia events. Moderate self-reported coffee consumption was associated with low risk of all dementia and non-Alzheimer's dementia, with a similar trend for Alzheimer's disease. Genetically predicted high coffee consumption was associated with high risk of all dementia (hazard ratio [95% confidence interval] per +1 cup/day: 1.20 [1.01–1.42]), with a similar trend for non-Alzheimer's dementia (1.23 [0.95–1.53]). High self-reported smoking was associated with high risk of non-Alzheimer's dementia. High genetically predicted smoking was associated with a trend towards high risk of all dementia and Alzheimer's disease (hazard ratios per +1 pack-year: 1.04 [0.96–1.11]) and 1.06 [0.97–1.16]). Moderate self-reported coffee consumption was associated with low risk of all and non-Alzheimer's dementia, while high genetically predicted coffee consumption was associated with a trend towards the opposite. High self-reported smoking was associated with high risk of non-Alzheimer's dementia, with a similar trend for genetically predicted smoking on all dementia and Alzheimer's disease. [Display omitted] • Moderate self-reported coffee consumption was associated with low risk of dementia. • High genetic coffee consumption showed a trend towards high risk of some dementia. • High self-reported smoking was associated with some dementia. • High genetic smoking showed a trend towards high risk of dementia. • High coffee consumption and smoking are unlikely to protect against dementia. [ABSTRACT FROM AUTHOR]