FURTHER THOUGHTS ON THE ALUMINUM-ALZHEIMERS DISEASE LINK

Study objective and method - The results of studies on aluminium (Al) and Alzheimer's disease (AD) from groups in Newcastle, UK and Ontario, Canada were compared in order to explain why the former were unable t o detect a link while the latter could, and to suggest alternative way s of examining the data. Results - The Al concentrations ire the Newca stle study were relatively small compared with the Ontario ones. When Al concentrations > 250 mu g/l were used, the RRs were greater for AD than for other forms of dementia, and the RRs were lower for those und er 75 years and greater at ages 85 years and over than at ages above 7 5 years. The relationship between dementia and Al concentrations was U or J shaped - there was a minimum at an Al concentration of 100 mu g/ l. Other constituents or properties such :is silicic acid, fluoride, t urbidity, iron, and pH all have an effect on the relationship. Conclus ions - Analyses of the type reported from Newcastle can yield further information if they are extended to include multivariate analyses that take account of other water constituents which can affect the relatio nship between ill water concentrations and AD are carried out. The rel ationship between Al and dementia may be U or J shaped rather than Lin ear. With regard to AD, the group aged less than 65 years is not the b est one in which to explore a relationship. Lastly, it may be that a l ink with AD is most meaningful at relatively high Al water concentrati ons.