American journal of epidemiology
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Meta Analysis
Smoking as a risk factor for dementia and cognitive decline: a meta-analysis of prospective studies.
The authors assessed the association of smoking with dementia and cognitive decline in a meta-analysis of 19 prospective studies with at least 12 months of follow-up. Studies included a total of 26,374 participants followed for dementia for 2-30 years and 17,023 participants followed up for 2-7 years to assess cognitive decline. Mean study age was 74 years. ⋯ Compared with those who never smoked, current smokers at baseline also showed greater yearly declines in Mini-Mental State Examination scores over the follow-up period (effect size (beta)=-0.13, 95% CI: -0.18, -0.08). Compared with former smokers, current smokers at baseline showed an increased risk of Alzheimer's disease (relative risk=1.70, 95% CI: 1.25, 2.31) and an increased decline in cognitive abilities (effect size (beta)=-0.07, 95% CI: -0.11, -0.03), but the groups were not different regarding risk of vascular dementia or any dementia. The authors concluded that elderly smokers have increased risks of dementia and cognitive decline.