Emerging Neurobiomarkers in Neurodegenerative Disorders: From Molecular Mechanisms to Clinical Translation

Neurodegenerative disorders such as Alzheimer’s Disease (AD) and Parkinson’s Disease (PD) are characterized by a progressive loss of neurons, correlating with loss of motor and cognitive function that has an impact on global health. Diagnosis of these diseases in clinical settings is generally delayed due to reliance on clinical features and diagnostic criteria that focus on symptomatic stages of the neurodegenerative disorder. Growing evidence suggests that pathological activity at a molecular level can occur years before the onset of symptoms. This narrative review focuses on recent progress in fluid, imaging, genetic, and multi-omics as well as digital biomarkers, with an emphasis on their diagnostic implementation, feasibility, value, and translation into clinical settings. In AD, cerebrospinal fluid and plasma biomarkers such as Glial Fibrillary Acid Protein (GFAP), Aβ1–42/Aβ1–40 ratios, and phosphorylated tau isomers (p-tau181, p-tau217) have been shown to have promising diagnostic relevance and utility. Protein Misfolding Cyclic Amplification (PMCA) and Real-Time Quaking-Induced Conversion (RT-QuIC) have shown high diagnostic specificity for detecting α-synuclein seeding activity, accurately distinguishing synucleinopathies, which are of particular interest in PD. Corresponding imaging biomarkers, including structural and functional MRI, Positron Emission Tomography (PET), and multimodal imaging, provide complementary insight into the relevance of disease-stage categorization. Multi-omics profiling and digital biomarkers, including wearable sensors, speech and gait analysis, and electroencephalography combined with artificial intelligence-driven pattern recognition, further broaden the biomarker terrain toward continuous, precision-based monitoring of neurodegeneration. Despite significant progress, limitations remain in standardization, biological heterogeneity, and validation of relevant findings. Ethical considerations related to preclinical diagnosis also require considerable premeditation. The change toward the implementation of a multimodal framework has the potential to shift neurodegenerative disease diagnosis from symptomatic late-stage diagnosis to early, molecularly mechanistic-driven medical aftermath.