Other CSF markers also showed a significant negative (but weaker) correlation with cognitive scores MMSE (O + C), although only in late PD: IL‐7 (r = −0.48), C‐C Motif Chemokine Ligand 2 (CCL2) (r = −0.33), IL‐8 (r = −0.32), and PIGF (r = −0.31) (Fig. 4E,F). Here, PIGF is linked to Parkinson disease.