MAPT and Alzheimer disease: Another study that assessed the association between soluble platelet-derived growth factor receptor (sPDGFR) levels in the CSF, CSF albumin, and the CSF/serum albumin ratio, the reduced CSF Aβ42 levels, and higher CSF total tau and p-tau levels in AD, also revealed a positive correlation between pericyte injury and BBB collapse, linked to the severity of AD [101].