SERPINE1 and Gliosis: Supporting this notion, it was found that increased PAI‐1 levels are present in regions where Aβ accumulates, such as cerebral cortex, but not in other brain Aβ‐free areas.46 In some rodent studies,42, 48 it was found that overproduction of PAI‐1 mainly occurs in the presence of gliosis associated with Aβ load.