Funding for this research was provided by:
Seventh Framework Programme (600841)
Michael J. Fox Foundation for Parkinson's Research (14446)
Received: 5 March 2019
Accepted: 8 July 2019
First Online: 16 July 2019
Ethics approval and consent to participate
: The study was carried out according to the Helsinki Declaration and was approved by the local Ethics committee (Ref.-No.213/08). All study participants gave written informed consent to participate in this study.
: Not applicable
: The authors declare that they have no competing interests.