Hippocampal atrophy can be associated with conditions other than Alzheimer's, such as stroke or CTE.

“now there are sometimes people who have hippocampal atrophy and turn out to be amyloid negative so there are these other pathologies that could be considered they call it hippocampal sclerosis some people have that from a stroke some people have it potentially from chronic traumatic encephalopathy and other other buildup of other abnormal proteins beside amyloid in the brain that kind of fact memory as well”