The quest for Parkinson's disease biomarkers: traditional and emerging multi-omics approaches.

Parkinson's disease (PD) is caused by the degeneration of dopaminergic neurons, leading to reduced dopamine levels and a wide range of motor and non-motor disorders contributing to disability and death. Unfortunately, there are no specific laboratory tests available for the early diagnosis of PD, and the cure is on hold. Given the heterogeneity of PD and overlapping symptoms with other disorders, one biomarker may not be sufficient for accurate diagnosis. Dopamine transporter imaging tests may be useful in diagnosis, but their utility is limited by factors such as availability, sensitivity, and resolution. Recent advances in testing, particularly those involving alpha-synuclein seed amplification, have shown promise. Given the heterogeneity of PD and overlapping symptoms with other disorders, one biomarker may not be sufficient for accurate diagnosis. Instead, a biomarker panel potentially incorporating multi-omics approaches will be needed. This panel should integrate various biomarkers derived from neuroimaging, oxidative stress, neuroprotection, and inflammation, tested from brain tissue, cerebrospinal fluid (CSF), blood, urine, and saliva. Multi-omics approaches and utilizing the exosomes could be beneficial, as exosomes protect their cargo from extracellular degradation and play a role in paracrine signaling that may contribute to disease progression. Our review discusses the current landscape of potential biomarkers for PD and highlights recent developments in this field. The identification of specific biomarkers representing disease onset, progression, and risk factors for PD is essential. A biomarker panel that incorporates multi-omics approaches and integrates various biomarkers from different sources may be the key to unlocking effective PD diagnosis and treatment strategies.