The sensitivity issue with NfL in diagnosing CBS-Aβ(–) was likely due to the fact that only very high NfL levels (IQR: 2.580–5.770, Table 5) strongly indicated CBS-Aβ(–), while lower levels overlapped with other groups such as HC (IQR: 1.390–2.620) and AD (IQR: 1.920–3.160), highlighting the need for additional biomarkers or alternative diagnostic approaches (Fig. 5 and Tables 10, 11, 12). Here, CBS is linked to Alzheimer disease.