GDNF and Parkinson disease: Another trial utilized bilateral, direct pump infusion of GDNF to the putamen of PD patients, and yielded a 39% decrease in off-medication UPDRS scores, a 64% reduction of L-DOPA induced dyskinesias, and a 28% increase of dopamine in the putamen 18 months following treatment, as measured by [18F]dopa positron emission tomography [124].