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> out of curiosity, have you worked with medical geography issues in PD > epidemiology? If so, is there something we should know about the > distribution of this condition? Hello Ansa, No, there do not seem to be any geographical issues in PD epidemiology, at least, not in Australia. My colleague and collaborator, Dr Simon Hammond MB BS (Lond) PhD (Syd) FRCP(UK) FRACP, had found a corollary with temperature gradations related to latitude in his definitive work on Multiple Sclerosis, where prevalence appeared to increase with distance from the equator. However, in Parkinson's Disease, where clusters of cases occurred, any apparent geological variations were filtered out by comparative analysis between quintiles by age and sex of actual Parkinson's sufferers, and matching quintiles of actual general population as noted in census data for the comparative period, any clustering became apparent at variations due to sociological aspects, rather than geographical ones. For example, where a raw data set for the Kimberley/Pilbara areas of Western Australia appeared to indicate an unusually low prevalence of PD, the adjusted data revealed that there was an anomaly in the population statistics, brought about by extensive migration of younger people to these areas to work in the mining industry. Similarly, there appeared to be an abnormally enhanced prevalence of PD in the Perth Hills district of Western Australia, this anomaly resolved, on examination, to be due to extensive migration of elderly people - those most likely to have PD - from other areas of the state to retire in the pleasant surroundings of this district. It became rapidly apparent, the longer this study continued, that using Standard Population data for the age comparison, and using estimated prevalence for the PD sufferers component, gave results that were much in variance with that data obtained from Government medical databases, and census material. It turned out that the prevalence as used in many papers on PD, could be shown to be vastly underated, with the official Australian-wide prevalence being in the order of 30,000 whereas our study showed the more accurate figure to be in the order of 85,000. An analysis of some 2,000 papers on PD prevalence show similar discrepancies, mostly bought about by methodology that was, to say the least, suspect. Sorry for such a long-winded answer, but as you can see, there is no simple answer to what is s very complex question> the one simple-seeming answer that I can give is that there were several anomalous clusters of increased prevalence, of statistical significance, whose only common factor was that they were areas in which the local drinking water supply was sourced form limestone predominate areas. Jim Slatttery ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn