The Mayo Clinic Family Study of Parkinson’s Disease: Study Design, Instruments, and Sample Characteristics

Abstract

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.

Complex segregation analysis of Parkinson's disease: The Mayo Clinic Family Study

“…following a standardized clinical assessment form. 26 The diagnostic criteria for PD were the same as those reported previously. 27 For the analyses, we distinguished a short-(120-mile radius around Rochester, MN) and a medium-distance referral region (fivestate region).…”

“…25,26 In brief, patients were administered a questionnaire including a detailed family composition section either directly or through a proxy. For some of the families of subjects who resided in Olmsted County and who had no available informant, the pedigree composition was obtained by linking existing obituary information and medical record information.…”

“…For some of the families of subjects who resided in Olmsted County and who had no available informant, the pedigree composition was obtained by linking existing obituary information and medical record information. 25,26 We considered ineligible for this study relatives who were younger than 40 at the time of the study (because of low risk for parkinsonism), half siblings, stepparents or step siblings, and adopted relatives (because there is no blood relation).…”

“…25,26 In brief, the primary methodology of the family study involved a two-phase design with individual screening of the relatives for parkinsonism and examination of those who screened positive. First-degree relatives were administered a screening instrument for parkinsonism through a direct telephone interview or through a proxy interview.…”

“…5,20 -24 The Mayo Clinic Family Study of Parkinson's Disease, using a combination of methods to directly study the relatives of cases and control subjects (family study method), showed a modestly increased risk in relatives of cases compared with relatives of control subjects. 25,26 In this article, we report the results of our complex segregation analyses. …”