A CLINICAL SURVEY OF PARKINSONISM IN ICELAND

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Abstract
The period of the survey chosen was 1954[long dash]1963 incl. During the survey, 470 cases of Parkinsonism were acknowledged, 258 or 54.89% were men and 212 or 45.11% women. There were 8 cases of idiopathic Parkinsonism where the disease began before the age of 30. It is difficult to distinguish between idiopathic and arteriosclerotic Parkinsonism. The average age at the onset of post-encephalitic Parkinsonism was 24.9. The period of time from the occurrence of encephalitis to the development of Parkinsonism was from less than 1 to 30 years, giving an average of 7.65 years. The average age at onset of the disease in the arteriosclerotic group was 68, and for those alive on the day of prevalence in the same group, 72. The average age at onset of the disease in the idiopathic group was 61.4, and for those alive in this group, on the day of prevalence, 68. The incidence of arteriosclerotic and idiopathic Parkinsonism (paralysis agitans) was 16 per 100,000. During the period of the survey, 1954[long dash]1963, there were considerably fewer Parkinsonism patients in the younger age-groups than during the years after epidemic of encephalitis in 1918. A considerably lower incidence for women only occurs in the age-group 40[long dash]49. The prevalence in all age-groups is 169.5 per 100,000, for men 180.9 and for women 158.0. The prevalence in the arteriosclerotic and idiopathic group (paralysis agitans) was 162.3. In the age-groups the prevalence steadily increases up to 70[long dash]79. For those over 50 years of age the prevalence is 762.6 per 100,000 (0.76%); for those over 60 years it is 1,196.1 per 100,000 (1.2%); and 2.3% of the population can be expected to develop Parkinsonism at some time or other during their lives. Death rates for Parkinsonism patients were 8.8 per 100,000. Parkinsonism was officially registered as the cause of death for only 1.8 per 100,000. In 94 cases (20%) hereditary factors were established. Essential tremor and senile tremor, typical and atypical Parkinsonism go together in families. The study of hereditary Parkinsonism in Iceland indicates an autosomal dominant inheritance of the disease. Recessive inheritance is unlikely, due to the vertical transmissions and sex-linkage which is excluded by the presence of normal daughters of affected males. Among 50 parents the total number of siblings was recorded, showing the ratio of 93 affected individuals against 253 normal. This high number of unaffected siblings as well as carrier parents of affected cases indicated a low penetrance. Multiple factors of inheritance can not be excluded.