Smoking and alcohol consumption as risk factors for later-life dementia

Aim: To investigate the risk of older age dementia associated with smoking and alcohol consumption. Method: Observational epidemiological studies were reviewed. Results: Case-control studies indicated that people who had ever smoked had a decreased risk of Alzheimer's dementia. However, the methodologically more sound cohort studies suggested that current smoking increases the risk of dementia. Most studies found no significant association between moderate alcohol use and the risk of dementia or other kinds of cognitive decline. The quantity of alcohol consumed and risk of dementia showed a U-shaped relationship. Conclusions: The results suggest that smoking increases the risk of dementia but that moderate consumption of alcohol is not substantially related to the incidence of dementia. It would be premature to conclude that drinking small quantities of alcohol has a protective effect.