Normal cerebrospinal fluid concentrations of PDGFRβ in patients with cerebral amyloid angiopathy and Alzheimer's disease

Background: Cerebrospinal fluid (CSF) platelet‐derived growth factor receptor‐β (PDGFRβ) has been proposed as a biomarker of blood–brain barrier (BBB) breakdown. We studied PDGFRβ levels as a biomarker for cerebral amyloid angiopathy (CAA), amnestic mild cognitive impairment (aMCI), or Alzheimer's disease (AD). Methods: CSF PDGFRβ levels were quantified by enzyme‐linked immunosorbent assay in patients with CAA, patients with aMCI/AD, and in matched controls. In aMCI/AD we evaluated CSF PDGFRβ both by clinical phenotype and by using the AT(N) biomarker classification system defined by CSF amyloid (A), tau (T), and neurodegeneration (N) biomarkers. Results: PDGFRβ levels were similar in CAA patients and controls (P = .78) and in aMCI/AD clinical phenotype and controls (P = .91). aMCI/AD patients with an AD+ biomarker profile (A+T+[N+]) had increased PDGFRβ levels compared to (A–T–[N–]) controls (P = .006). Conclusion: Our findings indicate that PDGFRβ levels are associated with an AD+ biomarker profile but are not a suitable biomarker for CAA or aMCI/AD clinical syndrome.