The Potential Use of Blood, Cerebrospinal Fluid, Saliva and Urine as Biological Samples for the Diagnosis of Alzheimer’s Disease

Background and Aim: Alzheimer’s disease (AD) is the most common cause of dementia. 80% of all dementia is due to AD. Diagnosis of AD is a difficult task, as the accurate diagnosis requires post-mortem examination of brain autopsy samples. Diagnosis of AD in living individuals can be aided by the establishment of the clinical criteria, positron emission tomography (PET) examination, and biomarkers. The study of biomarkers for diagnosis of AD could help clinicians to evaluate individuals at risk, and confirm the occurrence as well as the progression of AD in a non-invasive manner. High sensitivity and high specificity of the used markers are mandatory criteria for these biomarkers to trusted for AD diagnosis and prognosis. So, this review article aims to focus on the potential use of body fluids as a source of the biomarkers that are used for investigating patients with AD. Methodology: In the current study, we reviewed scientific articles that discuss AD pathogenesis and diagnosis of Google Scholar database, Pubmed, Pubmed Central, Cochrane Database of Systematic Reviews (CDSR), MEDLINE, and MedlinePlus with no time limitation. Moreover, we discussed the use of recently discovered biomarkers that are detected in blood, CSF, saliva, and urine. Conclusion: In the current review, it could be concluded that in addition to the blood and cerebrospinal fluid as common biological samples for the diagnosis of AD, saliva and urine are useful potential biological samples. Moreover, both are noninvasive samples that give them priority to be used.