MAPT and Alzheimer disease: Furthermore, when looking at the post-test probability in the CSF subsample, the pre-test probability of 67% for converting to AD within three years was increased by 21% using baseline BrainAGE scores (Figure 5B), but only slightly by using CSF biomarkers (T-Tau: 4%, P-Tau: 0%, Aβ42∶0%, Aβ42/P-Tau: 8%).