The epidemiology of Parkinson's disease in the Republic of Ireland: observations from routine data sources.

Routine data sources can provide clues to the temporal and geographical patterns of Parkinson's disease. Mortality trends show divergent age specific rates, with decreasing mortality for younger age-groups and increasing mortality for older age-groups. Cohort analysis showed a pattern consistent with the hypothesis that Parkinson's disease may have increased after the encephalitis lethargica pandemic. Hospital admission data suggest a rural excess of cases. The interpretation of this finding is complicated by the role of a variety of potential biases. Research is needed to examine urban-rural differences and environmental risk factors.