Parkinson's disease and parkinsonism in a longitudinal study: two-fold higher incidence in men. ILSA Working Group. Italian Longitudinal Study on Aging.

Objective: To determine the incidence of parkinsonism and PD in the Italian elderly, and to explore the relation with age and gender.

Methods: In eight Italian municipalities, a population-based, parkinsonism-free cohort was followed for an average of 3 years. At the end of the follow-up, the cohort survivors were directly contacted (screening and clinical examination). Cohort members who had died were studied using death certificates, clinical records, and information gathered from relatives and general practitioners. Parkinsonism diagnosis and subtyping were made according to specified diagnostic criteria.

Results: The cohort consisted of 4,341 individuals (65 to 84 years of age): 596 died before the examination, 2,863 (76.4% of the survivors) completed the screening procedure, and 882 refused to participate. The authors found 68 incident cases of parkinsonism: 42 PD (62%), 7 drug-induced parkinsonism (10%), 8 parkinsonism in dementia (12%), 8 vascular parkinsonism (12%), and 3 parkinsonism, unspecified (5.8%). Average annual incidence rate (per 100,000 person-years) in the population aged 65 to 84 years, adjusted to the 1992 Italian population, was 529.7 (95% CI, 400.5 to 658.9) for parkinsonism, and 326.3 (95% CI, 224.1 to 427.5) for PD. Incidence rates for both parkinsonism and PD increased with age in both men and women; men had higher rates in every age group. Age-adjusted relative risk in men compared with women was 1.66 (95% CI, 1.02 to 2.70) for parkinsonism and 2.13 (95% CI, 1.11 to 4.11) for PD.

Conclusions: Incidence of parkinsonism and PD increased with age, PD was the most common type of parkinsonism, and men had a risk of developing PD twice that of women.