GDNF and supranuclear palsy, progressive, 1: In PSP-P, in which the level of GDNF in the serum, is more elevated than in PSP-RS, however in both groups it is above the control level, the level of GDNF is positively correlated with the width of the third ventricle and MRPI 2.0 and negatively correlated with the parameters of MCP and M/P.