Interest in predictive testing for Parkinson's disease: impact of neuroprotective therapy.

As predictive testing for Parkinson's disease (PD) becomes available, it will be important to understand in whom such testing will be used. To address this issue, we conducted a mail survey of 138 first-degree relatives of PD patients. In the absence of treatment, 60% reported that they would either "definitely" or "probably" be interested in predictive testing. In the setting of a clinical trial, this number increased to 71% (p=0.04) and when neuroprotective therapy is available, interest increased to 90% (p<0.001). Interest in predictive testing for PD is moderate in the absence of effective therapy, and goes up significantly when both clinical trial participation and neuroprotective therapy are offered.