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Background: We reported high levodopa use and prevalences of Parkinson's Disease (PD) in periodically, time-clustered, icelandic cohorts born after major whooping cough epidemics (MWCE).Methods: In order to quantify a possible relationship between age at first post-birth MWCE and risk of PD we: 1) calculated cumulative incidences of PD during the period 1954-1963 in one-year Icelandic cohorts born between 1869 and 1927, using raw material from a reported survey; 2) identified MWCE from 1869 onwards in Iceland; 3) estimated cohort ages at onset of incidence period and at first MWCE; and 4) combined the above-mentioned information using log-linear models. In addition, we studied the prevalence of levodopa users in Icelandic birth cohorts during a recent period.Results: The curves of the above-mentioned incidences and prevalences in one-year birth-cohorts showed: 1) a similar, age-related, inverted V profile; and 2) a systematic notchy pattern, with peak values for one or both measurements for cohorts born during or after each of nine MWCE identified during the period 1869-1927. When 13 cohorts born in years with MWCE were excluded from the analysis, the risk of PD rose with age at first defined MWCE, with the linear increase being 8.4% per year (95% CI: -0.1-18.3%).Conclusions: These results are consistent with reported effects of age at exposure in animal models of toxic parkinsonism, age-related changes in the dopamine receptor-GPT-binding protein-adenylatecyclase system observed in rats treated with pertussis toxin, and some PD epidemiological features. They suggest that pertussis neurotoxicity could be casually treated to PD worldwide. [ABSTRACT FROM AUTHOR]

We evaluated levodopa use (LDU) by the Icelandic population focusing on: 1) annual gross levodopa (LD) sales from wholesalers to pharmacies for the period 1978-1990, using a reported method; 2) data from a prescription survey conducted from October 1st, 1990 to March 31st, 1991; and 3)raw and reported data on prevalences of Parkinson's disease (PD) in 1963 in this country. The standard for adjustments and reference population for LDU comparisons was the Swedish in 1984. Crude gross sales of LD in Iceland in 1990 and in Sweden in 1984 amounted to 1.67 and 1.35 DDD/1000 person days respectively. After respective adjustments for age, and for age and the infant mortality rates, taken as an indicator of health care quality, LDU in Iceland in 1990 was found to be 1.82 and 1.63 (95% CI 1.47-1.89) times that for Sweden. Prevalences of LD-prescription recipients in 1990-1991 and of PD in 1963 increased with age; however, those of drug users were higher than those of PD among the elderly. Higher-than-expected prevalences of PD and LD-prescription users (there being a partial overlap between these two categories) were found in periodically-clustered, one-year birth cohorts. These results support the notion that Iceland has a high LDU and suggest that this variation is due to a high prevalence of LD responsive disorders. Cohorts born after registered whooping cough outbreaks in Iceland may account for the magnitude and birth-related pattern of PD prevalences and LDU levels.