IGF1 and Parkinson disease: When considering IGF-1 quartiles as ordinal variable, MCP, bilateral fornix, cingulum, genu and body of the CC showed significantly negative association in PD, while splenium and bilateral corticospinal tracts were positively correlated with IGF-1 quartiles with P-values just below the significant threshold (FDR: 0.033 and 0.049, respectively).