The Role of CSF Biomarkers in Discriminating Between Cerebral Amyloid Angiopathy and Alzheimer’s Disease Patients: Systematic Review of Clinical Studies

Background: Alzheimer disease (AD), the most prevalent cause of dementia, is characterized by cognitive impairments and gradual memory loss. One of the most common neurological disorders affecting older people is cerebral amyloid angiopathy (CAA), which is defined by the buildup of amyloid β (Aβ) peptides in the walls of small and medium-sized cerebrocortical blood vessels as well as the leptomeninges. CAA and AD have several molecular, pathological, and clinical commonalities, like levels of Aβ peptides, total tau (t-tau), and phosphorylated tau (p-tau) in cerebrospinal fluid (CSF).  Objectives: The main objective of this study is to compare Aβ and tau protein indicators in the CSF of individuals with CAA or AD versus a healthy control group.  Materials Methods: Medline, Web of Science, Google Scholar, and Embase databases were searched for relevant studies published from 2009 to 2022. Ten observational studies that reported the levels of t-tau, p-tau, Aβ40, Aβ42, or Aβ42/Aβ40 ratio in the CSF of AD and CCA patients were included.  Results: The results showed that CAA and AD patient groups have higher p-tau and t-tau levels than the control group. Significantly lower concentrations of t-tau, p-tau, and Aβ40 are observed in the CSF of CAA compared to AD patients.  Conclusion: We found that CSF p-tau, t-tau, and Aβ40 levels as reliable biomarkers can help diagnose and differentiate AD and CAA. Our study indicates that CSF biomarkers t-tau, p-tau, Aβ40, and Aβ42/Aβ40 ratio can be used in the clinical setting to distinguish between CAA and AD.