A novel approach to correlate the salivary exosomes and their protein cargo in the progression of cognitive impairment into Alzheimer’s disease

•Early screening is essential as behavioural symptoms appears in later stage.•Concentration of salivary exosomes corroborates with disease severity.•Increased expression of p-tau and low weight oligomeric Aβ in early stages.•High weight oligomeric form of Aβ in Alzheimer’s disease patients.