Table 2.

High-citation studies on molecular biomarkers for early detection and diagnosis.

Biomarker Type	Primary Marker(s)	Associated Disease(s)	Detection Method	Diagnostic Value	High-Citation Studies
Protein aggregates	Amyloid-beta, tau	Alzheimer’s	CSF analysis, PET imaging	High sensitivity and specificity for early AD diagnosis	Chapleau et al. (2022) [365], Greenberg et al. (2022) [366]
Inflammatory cytokines	TNF-α, IL-1β, IL-6	ALS, Alzheimer’s, PD	Blood-based biomarkers, CSF sampling	Elevated levels correlating with neuroinflammatory activity	Heneka et al. (2015) [88], Hu et al. (2017) [367]
Genetic mutations	SOD1, HTT, APOE ε4	ALS, Huntington’s, AD	Genotyping, next-gen sequencing	APOE ε4 for AD risk; SOD1 mutations in familial ALS	Serrano-Pozo et al. (2021) [368], Renton et al. (2014) [369]
Oxidative stress markers	8-OHdG, MDA, protein carbonyls	ALS, Huntington’s	Urine, blood assays	Indicative of oxidative damage in early neurodegeneration	Beal et al. (2005) [370], Chen et al. (2004) [371]
Synaptic loss indicators	Synaptophysin, PSD-95	Alzheimer’s, Parkinson’s	Immunohistochemistry, PET tracers	Correlates with cognitive decline and synaptic dysfunction	Tzioras et al. (2023) [372], Dauer et al. (2003) [95]