Extracellular vesicles, new actors in the search for biomarkers of dementias.

Increased life expectancy impacts directly on the number of older people worldwide with the associated increase in neurodegenerative diseases. Besides their social implications, the different forms of dementia, including Alzheimer's disease, Parkinson's disease, dementia with Lewy bodies or frontotemporal dementia, show clinical and pathological overlaps; this hinders their specific and differential diagnosis. To date, biomarkers for each of these types of dementia have been investigated in the cerebrospinal fluid or blood. More recently, the field of biomarker search found a new opportunity to improve diagnosis in extracellular vesicles (EVs). EVs are released by cells including those of the central nervous system and these can be isolated from cerebrospinal fluid and blood. This review summarizes the current knowledge related to the search for dementia biomarkers in the field of EVs including studies of specific EV content, mainly proteins such as α-synuclein or tau and RNA species.