CCL4 and Cognitive impairment: Additionally, PARK6-associated PD patients have also shown PINK1 deficiency and its impact on increased generation of pro-inflammatory cytokines and chemokines (e.g., IFNβ1, IL-6, IL-12, IL-13, CCL2, CCL4, and CXCL1), loss of NCs, and the development of cognitive defects (Table 6B).