CBS and Alzheimer disease: It is worth acknowledging that compared to their CSF counterpart, plasma amyloid ratios showed narrow interquartile ranges (e.g. AD 0.113–0.122, HC 0.129–0.141), small standard deviations (e.g. AD 0.007, HC 0.019) and substantial overlap in IQRs, e.g. between HC and CBS-Aβ(–) (0.127–0.135), which may limit their diagnostic utility by reducing the ability to clearly differentiate between groups.