Silica present in drinking water may be protective with respect to the decrease of cognitive function as it was suggested by several epidemiologic studies. Data from French cohort have demonstrated that aluminium in drinking water seems to have a deleterious effect and increased the risk of cognitive impairment when the silica concentrations were low. Moreover, it has been shown that the performances to a cognitive test were positively correlated to the consumption of silica and that the risk of Alzheimer's disease (AD) was reduced in subjects who had the higher daily silica intake compared to the others. The silica is probably the natural antidote of the aluminium and could play a benefit role by decreasing the biodisponibility of aluminium, whose neurotoxicity is now clearly established. Data have suggested the possible use of silicates as a therapeutic agent for AD since both model tangles and precipitated beta-pleated sheets of betaA4 can be reversed to soluble forms by silicates. The role of silica in drinking water on cognitive function has been however little studied and clear results have not yet emerge. The potential benefit of silica needs to be confirmed in additional investigations to exclude causes of error related to certain methodological biases. If such association do indeed exist, interventional strategies could be set up to reduce the incidence of AD. The aim of this paper is to review articles published on silica present in drinking water in relation with AD and associated disorders.