CCL2 and Cognitive impairment: The blood, brain regions, and cells of the mouse model of PARK6-associated PD have shown PINK1 deficiency and its impact on increased blood or brain generation of pro-inflammatory cytokines and chemokines (e.g., IFNγ, IFNβ1, TNFα, IL-1β, IL-2, IL-6, IL-10, IL-12, IL-13, IL-17, TGFβ, CCL2, CCL4, and CXCL1), loss of neuronal cells, and the development of cognitive defects in PD (Table 6A).