Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Ruth Schneider reports a relationship with National Institutes of Health that includes: funding grants. Ruth Schneider reports a relationship with Michael J Fox Foundation for Parkinson's Research that includes: funding grants. Ruth Schneider reports a relationship with CHDI Foundation that includes: funding grants. Ruth Schneider reports a relationship with Biohaven Pharmaceuticals that includes: funding grants. Ruth Schneider reports a relationship with ACADIA Pharmaceuticals Inc that includes: funding grants. Ruth Schneider reports a relationship with Sun Pharma Advanced Research Centre that includes: consulting or advisory. Ruth Schneider reports a relationship with Clintrex that includes: board membership.