A group of patients with idiopathic PD and with bilateral STN DBS implant (experimental group) and a control group including patients with idiopathic PD and without DBS implant who are treated with dopaminergic medications will be recruited from the IRCCS Fondazione Ca' Granda Ospedale Maggiore Policlinico of Milan and from the Istituto Neurologico Nazionale IRCCS Casimiro Mondino of Pavia. Patients will be selected in order to balance groups for gender, age, disease duration, cognitive and motor functions.