Similar studies in PD have yielded different results; Scalzo et al. found no significant correlations between serum IL-6 and PD symptom severity (UPDRS-3, Hoehn & Yahr, and Schwab & England) [18], while Menza et al. found a positive correlation between TNF-α and Schwab & England ADL scale scores, but not with UPDRS [19]. Here, TNF is linked to Parkinson disease.