MAPT and Apathy: One possible explanation for this finding is that because the non-apathy MBI group (comprising individuals with MBI-affect, MBI-impulse dyscontrol, MBI-social inappropriateness and/or MBI-psychosis) was not associated with tau biomarkers, unlike the full MBI construct in our previous study,30 it might be that the MBI-apathy domain plays a contributing role in linking MBI to these biomarkers.