Proteome-Based Biomarkers for Alzheimer’s Disease: Old Acquisitions and Innovative Proposals

Alzheimer’s disease (AD) is one of the most widespread neurodegenerative disorders, primarily affecting individuals over the age of 65. It is characterized by severe cognitive impairment, memory loss, difficulties in performing daily activities, ventricular enlargement, and ultimately, dementia. AD is associated with the accumulation of amyloid $\beta \left(A\beta \right)$ protein plaques, intracellular neurofibrillary tangles (NFTs), progressive inflammation, and impairment of both synaptic transmission and mitochondrial function. Due to the limited diagnostic tools available for detecting the disease in its early stages, proteomic biomarkers have gained paramount importance, as they can monitor prodromal molecular alterations linked to AD. Furthermore, proteomic biomarkers can facilitate the longitudinal assessment of disease progression and contribute to the development of personalized therapeutic strategies before the devastating onset of dementia. Research has primarily focused on identifying proteomic biomarkers in cerebrospinal fluid (CSF) and plasma, as discussed in this review, but also in alternative matrices such as saliva and urine. These studies highlight both the high potential of proteomic approaches and the ongoing challenge of identifying clinically available, sensitive, and specific biomarkers for the various stages of the disease.