Components of drinking water and risk of cognitive impairment in the elderly.

The relation between aluminum, fluorine, calcium, and pH in drinking water and the risk for cognitive impairment was studied using data collected in 1988-1989 in a population-based survey of 3,777 French men and women aged 65 years and older (the Paquid study). Cognitive impairment was defined as a score lower than 24 on the Mini-Mental State Examination. Data related to drinking water came from two prospective measurement surveys whose reliability was checked by a variability study. A mixed effects logistic regression was performed, adjusting for the effects of the age, sex, educational level, and occupation of the participants. A significant protective effect was found for high calcium concentration (odds ratio = 0.8 for a concentration > or = 75 mg vs. < 75 mg, p = 0.015). For aluminum, no significant effect was found when pH was not included in the model, but the results showed a weak interaction between aluminum and pH. When the four variables (calcium, aluminum, pH, and aluminum x pH interaction) were considered in the statistical analysis as a group, this group was significantly related to cognitive impairment (p = 0.01).