Stage I chronic traumatic encephalopathy. In stage I chronic traumatic encephalopathy, phosphorylated tau (p-tau) pathology is found in limited discrete perivascular foci (A), typically at the depths of sulci or around small vessels (black circles). There is limited p-tau pathology in the cortex adjacent to the involved foci (B). Occasional p-tau neurites are found in the nucleus basalis of Meynert (C). There is no pathology in the amygdala (D) or CA1 of the hippocampus (E). CP-13-immunostained 50 μm tissue sections, some counterstained with cresyl violet. Scale bar = 100 μm. Adapted from .