Tobacco use and dementia: evidence from the 1066 dementia population-based surveys in Latin America, China and India.

OBJECTIVE

To assess the association between tobacco consumption and dementia using the same methodology in seven developing countries, testing the specific hypotheses that higher exposure to tobacco is associated with a higher prevalence of dementia, that the association is limited to smoked tobacco and is stronger for vascular dementia compared to Alzheimer's disease.

METHODS

Cross-sectional surveys conducted on individuals aged 65+. A total of 15 022 residents in specified catchment areas were assessed face-to-face using a standardised protocol, which included dementia diagnosis and detailed information on past and current tobacco consumption, and on important potential confounders of this association.

RESULTS

A high proportion of participants were never smokers (52% in Dominican Republic to 83% in Peru), most of those who ever used tobacco in China and India were still smoking at age 65 and above (80% and 84%, respectively). There was a positive association between history of tobacco smoke exposure (pack years up to age 50) and dementia (pooled PR = 1.003; 95%CI 1.001-1.005), Alzheimer's disease (pooled PR = 1.007; 95% CI, 1.003-1.011) and Vascular Dementia (pooled PR = 1.003; 95% CI = 1.001-1.005). These associations were attenuated but remained significant if exposure after the age of 50 was included. In India there was no association between smokeless tobacco and dementia.

CONCLUSIONS

Dementia in developing countries appears to be positively associated with history of tobacco smoking but not smokeless tobacco use. Selective quitting in later life may bias estimation of associations.