Figure 1.

Flow diagram of the study sample: from assessment for the study to the final analytic sample. *Eligible DBS+ patients were PD patients who had surgery scheduled in one of the participating institutions and who could be contacted by the study team prior surgery. Eligible participants for the control group were selected among PD patients who were not expected to require DBS within two years of enrollment in the study. ^§diagnosis was revised by the clinician’s patient. †no post‐baseline assessment available.