MAPT and Apathy: However, we found the mediation effect of other Aβ pathology biomarkers, including CSF Aβ42/t-tau ratio (Fig. 3A1, A2), frontal lobe Aβ burden (Fig. 3B1, B2), left mOFC Aβ burden (Fig. 3C1, C2), and right POC Aβ burden (Fig. 3D1, D2), which mediated the association between apathy severity and cognitive impairment after 2 years (ADAS-13 and FAQ).