Silicon may prevent Alzheimer's disease
Dr. Sophie Gillette-Guyonnet of Caseradite Hospital in Toulouse and colleagues studied women participating in the Epidemiological Study of Osteoporosis (EPIDOS). The study included 7,598 women aged 75 and over from five cities in France, whose intellectual acuity was measured at the beginning of the study between 1992 and 1994.
Their water intake (tap water or mineral water) was determined through a questionnaire, and data on silica, calcium and aluminum contents were obtained from local water companies and mineral water distribution companies.
Women with normal or higher intellectual functioning at the outset had higher daily silica intake, and this relationship remained statistically significant after accounting for age, location, income, education, and stroke history.
In the second phase of the study, the researchers followed women living in Toulouse who had normal or higher cognitive scores for seven years. During this time, 60 women developed Alzheimer’s disease, while 323 women maintained normal cognitive function.
The researchers found that women with Alzheimer’s were 2.7 times more likely to have lower daily silica intake than those without the disease. They believe that silica is a “natural antidote” for aluminum, which is linked to the formation of so-called senile plaques in the brain. However, in the current study, there appeared to be no relationship between aluminum in drinking water and cognitive function—but the aluminum levels in the study group were very low.
Background: Aluminum or silica concentrations in drinking water may be potential environmental risk factors for Alzheimer’s disease (AD).
Objective: The objectives were to investigate potential associations between drinking water composition and cognitive function levels in women participating in the Epidemiology of Osteoporosis (EPIDOS) study at baseline and to determine the effect of drinking water composition on AD risk during follow-up.
Setting: Women aged 75 years (n = 7598) were recruited between 1992 and 1994 in 5 geographic regions of France. Participants (n = 1462) from a single center were followed for 7 years; during this time, incident cases of Alzheimer’s disease were actively searched for. The initial questionnaire included a food consumption survey that specifically asked about daily consumption of tap and mineral water. Assessment of cognitive function was based on the Mini-Mental State Questionnaire. During the follow-up period, dementia was diagnosed by geriatricians and neurologists.
Results: Low silica concentrations were associated with lower baseline cognitive performance. Compared with non-dementia participants, women diagnosed with Alzheimer’s disease during follow-up were older at enrollment, had lower economic status and education, had poorer perceptions of their health status, and experienced more difficulties in performing activities of daily living. Multivariate analysis including potential confounders showed that women with AD appeared to have lower exposure to silica at baseline.
Conclusion: Silica in drinking water can reduce the risk of Alzheimer’s disease in elderly women. This result confirms the findings of another epidemiological study conducted in France. The potential impact of silica needs to be confirmed in further investigations.
Sources:
Sophie Gillette-Guyonnet, Sandrine Andrieu, Fatemeh Nourhashemi, Viviane de La Guéronnière, Hélène Grandjean and Bruno Vellas; Cognitive impairment and composition of drinking water in women: findings of the EPIDOS Study; American Journal of Clinical Nutrition, Vol. 81, No. 4, 897-902, April 2005.
