Is there an association between smoking and a reduced risk of developing dementia?

From the Guidelines

Smokers do not have a lower risk of dementia; in fact, smoking is a significant risk factor for developing dementia. According to a recent review and synthesis published in the Journal of Internal Medicine in 2021 1, avoiding smoking uptake and supporting smoking cessation is crucial, as stopping smoking reduces the risk of dementia even in later life. The evidence suggests that smoking is a modifiable risk factor for dementia, and addressing it, along with other risk factors such as hypertension, hearing loss, and obesity, can significantly reduce the risk of developing dementia. Some key points to consider include:

• Reducing exposure to air pollution and second-hand tobacco smoke is essential for preventing dementia
• Limiting alcohol use and preventing head injury are also critical in reducing the risk of dementia
• Sustaining midlife and possibly later-life physical activity, and addressing other putative risk factors for dementia, such as sleep, through lifestyle interventions, can improve general health and reduce the risk of dementia
• Multimodal intervention, which involves addressing multiple risk factors at once, is more efficacious than unimodal interventions in reducing the risk of dementia The benefits of quitting smoking are clear, and stopping smoking reduces the risk of dementia even in later life 1. Therefore, it is essential to prioritize smoking cessation and address other modifiable risk factors to reduce the risk of developing dementia.

From the Research

Association Between Smoking and Dementia Risk

• There is no evidence to suggest that smoking is associated with a reduced risk of developing dementia. In fact, studies have consistently shown that smoking is associated with an increased risk of dementia, Alzheimer's disease, and vascular dementia 2, 3, 4.
• A study published in 2008 found that long-term cigarette smoking may raise the risk of disabling dementia, with a dose-response relationship noted between the years of cigarette smoking and the risk of total dementia 2.
• Another study published in 2018 found that smokers who quit for a prolonged period of time may benefit from reduced risk of dementia, with long-term quitters and never smokers having decreased risk of overall dementia, Alzheimer's disease, and vascular dementia compared to continual smokers 3.
• Heavy smoking in midlife has also been associated with a greater than 100% increase in risk of dementia, Alzheimer's disease, and vascular dementia more than 2 decades later 4.
• Additionally, exposure to environmental tobacco smoke has been linked to an increased risk of dementia and Alzheimer's disease among never smokers, with the risk increasing with exposure duration and cumulative exposure dose 5, 6.

Key Findings

• Smoking is associated with an increased risk of dementia, Alzheimer's disease, and vascular dementia 2, 3, 4.
• Quitting smoking for a prolonged period of time may reduce the risk of dementia 3.
• Heavy smoking in midlife is associated with a greater than 100% increase in risk of dementia, Alzheimer's disease, and vascular dementia more than 2 decades later 4.
• Exposure to environmental tobacco smoke is linked to an increased risk of dementia and Alzheimer's disease among never smokers 5, 6.