In a study analyzing cerebral spinal fluid (CSF) concentrations of different interleukins and cytokines in patients with PD and atypical parkinsonian syndromes, it was revealed that PSP and MSA populations had significantly higher levels of C-reactive protein (CRP), TNF-α, IL-1β, IL-4, and IL-6 than the PD and control groups [16]. Here, CRP is linked to Parkinson disease.