Koffie et al. (2012) estimated that 18–34% of all synapses in brain are positive for ApoE. Another study found that in AD post-mortem brains, 90% of the synapsotomes that are positive for ApoE receptors LRP1 or LDLR are also positive for ApoE, compared to 21% ApoE-positivity in the total synaptosome population (Bilousova et al., 2019). Here, APOE is linked to Alzheimer disease.