Novel Blood Biomarkers for an Earlier Diagnosis of Alzheimer’s Disease: A Literature Review

Abstract

Alzheimer’s disease is a neurodegenerative condition associated with neurofibrillary tangles and cortical deposition of amyloid plaques. Clinical presentation of the disease involves manifestations such as memory loss, cognitive decline and dementia with some of the earliest reported deficits being episodic memory impairment and olfactory dysfunction. Current diagnostic approaches rely on autopsy characterization of gross brain pathology, or brain imaging of biomarkers late in the disease course. The aim of this literature review is to identify and compare newly emerging and novel CSF, serum and mucosal biomarkers, with the potential of making an earlier clinical diagnosis of Alzheimer’s disease. Utilizing such techniques may allow for earlier therapeutic intervention, reduction of disability and enhancement of quality of life. Literature review and analysis was performed by screening the PubMed database for relevant studies within the past 5 years. All studies showed statistically significant (P < 0.05) differences in testing between AD patients and controls. Two categories of serum biomarkers (redox-reactive antiphospholipid antibodies and microRNAs) and an olfactory mucosal marker (microRNA-206) could discriminate between early AD patients and controls with high sensitivity and specificity. In conclusion, certain studies have shown promising results with high sensitivity and specificity, high discriminative potential for Alzheimer’s disease early in its progression, and statistically significant results in larger study samples. Utilization of such diagnostic techniques should increase the efficacy of making an earlier clinical diagnosis of Alzheimer’s disease.