MCP-1, also known as C-C motif ligand 2 (CCL2), has been described as a biomarker of neuroinflammation, and its concentrations in blood and cerebrospinal fluid have been found to increase in patients with various neurological diseases, including Parkinson’s disease, multiple sclerosis, ischemic stroke, and traumatic brain injury [45,46]. Here, CCL2 is linked to Parkinson disease.