Leaky BBB and Toxic Fibrinogen Linked with Early Stages of Dementia
"....... death of pericytes in the smallest brain blood vessels leads to a leaky blood–brain barrier (BBB), which reduces blood flow and allows the accumulation of blood-derived, toxic fibrinogen in the brain. The chain of events caused by the death of pericytes links small vessel disease with white matter disease, which are associated with AD and dementia in the elderly."
https://www.genengnews.com/gen-news-highlights/leaky-bbb-and-toxic-fibrinogen-linked-with-early-stages-of-dementia/81255460

Scientists say leaky blood vessels and the accumulation of fibrinogen in the brain underpin the development of Alzheimer's disease and other dementias