The Mayo Clinic family study of Parkinson's disease: study design, instruments, and sample characteristics.

We describe here the Mayo Clinic Family Study of Parkinson's disease (PD), including the overall study design (historical cohort study of relatives from birth to onset of PD or censoring), the data collection instruments, the strategies implemented to prevent or measure biases, and the sample obtained. These methodological details may provide assistance to other investigators designing studies of the familial aggregation of PD or other aging-related chronic diseases. We investigated the incidence of PD and other neurodegenerative diseases among 1,001 first-degree relatives of 162 patients with PD and 851 relatives of 147 controls representative of the population of Olmsted County, Minn., USA. In addition, we studied 2,713 first-degree relatives of 411 patients with PD referred to the Mayo Clinic. Finally, we studied a group of 625 spouses of either cases or controls. Relatives with PD or other neurodegenerative diseases were ascertained using the family study method.