Changing epidemiology of Parkinson's disease in southwestern Finland

Objective: Investigation of the epidemiology of PD in southwestern Finland in 1992 (population 196,864), including urban and rural areas, with a compa rison with a similar study, done in the same area in 1971, to evaluate the temporal pattern. Methods: Community-based method of patient ascertainment with personal investigation of cases. Results: The age-adjusted prevalence (to the Finnish general population in 1991) was 139 per 100,000 population in 1971 and 166 in 1992. Prevalence ratio for PD in men versus women was 1. 2 (NS) in 1971 and 1.7 in 1992 (p < 0.001); in the rural versus urban popul ations the prevalence ratio was 0.8 (NS) in 1971 and 1.3 in 1992 (p = 0.013 ). The age-specific prevalence rates showed a male preponderance in all age groups in 1992 and a rural preponderance in the age groups over 60 years. In 1992, compared with 1971, the male and rural preponderance occurred in t he age groups over 70 years. The age-adjusted incidence was 15.7 per 100,00 0 population in 1971 and 14.9 in 1992. Relative risk for PD in men versus w omen was 0.9 (NS) in 1971 and 1.9 (p < 0.001) in 1992, and in rural versus urban populations 1.4(p = 0.093) in 1992. Conclusions: A very significant m ale and a significant rural predominance, not seen in 1971, suggests a poss ible environmental causative factor, perhaps more frequent in the rural env ironment, associated with PD. Men may be either more exposed to it or more susceptible to its effects than women.