Clinical biomarkers: (i) Motor symptoms such as bradykinesia, rigidity, tremor, and postural instability are hallmark clinical manifestations of PD and are used in diagnosis and monitoring disease progression; (ii) Non-motor symptoms, including cognitive impairment, psychiatric symptoms, autonomic dysfunction, and sleep disturbances, may serve as biomarkers for PD severity and progression. Neuroimaging biomarkers: (i) Dopamine transporter (DAT) imaging with single-photon emission computed tomography (SPECT) or positron emission tomography (PET) can assess presynaptic dopaminergic function and differentiate PD from other parkinsonian syndromes; (ii) Functional MRI (fMRI) can evaluate changes in brain activity and connectivity patterns associated with PD, providing insights into disease pathophysiology and compensatory mechanisms; (iii) Structural MRI techniques, such as volumetric analysis and diffusion tensor imaging (DTI), can detect changes in brain morphology, white matter integrity, and gray matter density associated with PD. Cerebrospinal fluid (CSF) biomarkers: (i) Measurement of α-Synuclein levels or specific αsynuclein species (e.g., oligomeric forms) in CSF may reflect underlying pathology and serve as a diagnostic or prognostic biomarker for PD; (ii) Elevated levels of Tau and phosphorylated Tau (p-Tau) in CSF have been reported in PD patients and may indicate neurodegeneration and tau pathology. Blood-based biomarkers: (i) Blood-based assays for α-Synuclein levels and post-translational modifications are under investigation as potential biomarkers for PD. However, blood-based αsynuclein assays have been challenging due to low concentrations and high variability; (ii) Biomarkers of neuroinflammation, such as cytokines, chemokines, and inflammatory mediators, have been proposed as potential indicators of disease activity and progression in PD. Genetic biomarkers: (i) Genetic variants associated with PD risk identified through genomewide association studies (GWAS) and next-generation sequencing may serve as genetic biomarkers for disease susceptibility and progression; (ii) Pathogenic monogenic mutations in genes such as SNCA, LRRK2, PARK2, and GBA are associated with familial forms of PD and may serve as biomarkers for genetic testing and personalized risk assessment. Peripheral biomarkers: (i) Olfactory dysfunction, commonly observed in PD patients, may serve as a peripheral biomarker for early disease detection and monitoring; (ii) Alterations in gut microbiota composition and metabolites have been reported in PD patients and may represent peripheral biomarkers of disease risk and progression.