Cognitive impairment and composition of drinking water in women:: findings of the EPIDOS Study

Background: The concentration of aluminum or silica in drinking water may be a potential environmental risk factor for Alzheimer disease (AD). Objectives: The objective was to investigate at baseline the potential association between the composition of drinking water and the level of cognitive function in women taking part in the Epidemiology of Osteoporosis (EPIDOS) Study and to determine during follow-up the effects of the composition of drinking water on the risk of AD. Design: Women aged >= 75 y (n = 7598) were recruited between 1992 and 1994 in 5 geographic areas of France. The participants from one center (n = 1462) were followed for ! 7 y; during this time, an active search for incident cases of AD was conducted. The initial questionnaire comprised a food consumption survey with specific questions about the daily consumption of tap and mineral water. The evaluation of cognitive function was based on the Short Portable Mental Status Questionnaire. During follow-up, the diagnosis of dementia was made by a geriatrician and a neurologist. Results: A low silica concentration was associated with low cognitive performance at baseline. Compared with the nondemented subjects, the women with a diagnosis of AD during follow-up were older at inclusion, had a lower financial status and educational level, had a poorer perception of their own health, and had a more difficult time performing activities of daily living. A multivariate analysis including potential confounding factors showed that women with AD appeared to have been exposed to lower amounts of silica at baseline. Conclusions: Silica in drinking water may reduce the risk of developing AD in elderly women. The results corroborate those of another epidemiologic study carried out in France. The potential effect of silica needs to be confirmed in additional investigations.