Age, sex, and cerebral microbleeds in EFAD Alzheimer disease mice

Cerebral microbleeds (MBs) increase at later ages in association with increased cognitive decline and Alzheimer Disease (AD). MB prevalence is also increased by APOE4 and hypertension. In EFAD mice (5XFAD(+)(/-)/human APOE(+/+)), cerebral cortex MBs are most prevalent in E4 females at 6 months, paralleling plaque amyloid. We evaluated MBs at 2, 4, and 6 months in relation to amyloid in plaques and cerebral amyloid angiopathy (CAA) by age, sex, APOE allele, and blood pressure. At 2 mo, MBs were 50% more numerous than plaques, followed by decreased ratio of MBs:A beta plaques with female excess to 6 mo. The stable size of MBs suggests MBs arise as single events of extravasation, which may seed plaque formation. Blood pressure was normal from 2 to 6 months, minimizing a role of hypertension. Memory, assessed by fear conditioning, decreased with age in correlation with MBs and amyloid. Cortical layer analysis showed prevalent MBs and plaque in layers 4 and 5. Contrarily, CAA was prevalent in layers 1 and 2, discounting its contribution to MBs. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

Cerebral microbleeds increase with age, associated with cognitive decline and Alzheimer's Disease, influenced by APOE4 and hypertension. In a mouse study, microbleeds were most prevalent in the cerebral cortex of E4 females. Blood pressure did not affect the occurrence of microbleeds in the study.