Biomarkers in Parkinson’s disease (recent update) (original) (raw)

2013, Neurochemistry International

Parkinson's disease (PD) is the second most common neurodegenerative disorder mostly affecting the 29 aging population over sixty. Cardinal symptoms including, tremors, muscle rigidity, drooping posture, 30 drooling, walking difficulty, and autonomic symptoms appear when a significant number of nigrostriatal 31 dopaminergic neurons are already destroyed. Hence we need early, sensitive, specific, and economical 32 peripheral and/or central biomarker(s) for the differential diagnosis, prognosis, and treatment of PD. 33 These can be classified as clinical, biochemical, genetic, proteomic, and neuroimaging biomarkers. Novel 34 discoveries of genetic as well as nongenetic biomarkers may be utilized for the personalized treatment of 35 PD during preclinical (premotor) and clinical (motor) stages. Premotor biomarkers including hyper-ech-36 ogenicity of substantia nigra, olfactory and autonomic dysfunction, depression, hyposmia, deafness, REM 37 sleep disorder, and impulsive behavior may be noticed during preclinical stage. Neuroimaging biomark-38 ers (PET, SPECT, MRI), and neuropsychological deficits can facilitate differential diagnosis. Single-cell pro-39 filing of dopaminergic neurons has identified pyridoxal kinase and lysosomal ATPase as biomarker genes 40 for PD prognosis. Promising biomarkers include: fluid biomarkers, neuromelanin antibodies, pathological 41 forms of a-Syn, DJ-1, amyloid b and tau in the CSF, patterns of gene expression, metabolomics, urate, as 42 well as protein profiling in the blood and CSF samples. Reduced brain regional N-acetyl-aspartate is a bio-43 marker for the in vivo assessment of neuronal loss using magnetic resonance spectroscopy and T 2 relax-44 ation time with MRI. To confirm PD diagnosis, the PET biomarkers include [ 18 F]-DOPA for estimating 45 dopaminergic neurotransmission, [ 18 F]dG for mitochondrial bioenergetics, [ 18 F]BMS for mitochondrial 46 complex-1, [ 11 C](R)-PK11195 for microglial activation, SPECT imaging with 123 Iflupane and bCIT for dopa-47 mine transporter, and urinary salsolinol and 8-hydroxy, 2-deoxyguanosine for neuronal loss. This brief 48 review describes the merits and limitations of recently discovered biomarkers and proposes coenzyme 49 Q 10 , mitochondrial ubiquinone-NADH oxidoreductase, melatonin, a-synculein index, Charnoly body, 50 and metallothioneins as novel biomarkers to confirm PD diagnosis for early and effective treatment of PD.