Whether lipid metabolism factors can be utilized as PD disease severity biomarkers have not been clarified, although a study from Parkinson’s Progression Markers Initiative (PPMI) showed that lower serum apolipoprotein A1 (Apo-A1) levels were associated with earlier age of PD onset and greater motor severity in drug-naïve PD [12]. Here, APOA1 is linked to Parkinson disease.