Biochemical biomarkers
Biochemical biomarkers are collected from body fluids, such as the cerebrospinal fluid (CSF), blood, saliva and urine, or tissue biopsies such as skin, and analyzed using molecular biology techniques [10-12]. Indeed, such biomarkers are easily accessible without risky procedures, but sensitivity and specificity issues might limit their utility [13]. In this respect CSF and blood biomarkers reflecting the pathophysiology of PD, such as alpha-synuclein (a-syn) species, lysosomal enzymes, neurofilaments and markers of beta-amyloid (Aβ) and tau pathology are obvious candidates [9, 14]. There is only a limited number of studies with focus on serum or plasma biochemistry during experimental PD [15].