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How might early hippocampal hyperactivity contribute to later Alzheimer disease?
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Alzheimer disease
Histopathologic image of neuritic plaques in the cerebral cortex in a patient with Alzheimer disease of presenile onset (onset before age 65).
In individuals who carry the APOE4 genetic variant, research using functional magnetic resonance imaging (fMRI) has observed increased activity in the hippocampus as early as ages 20 to 35.1
Scientists hypothesize that this early-life hippocampal hyperactivity may lead to the eventual dysfunction of the region. This progressive decline in hippocampal function is a hallmark of Alzheimer disease, where the region undergoes massive cell loss, contributing to the characteristic memory deficits observed in the disease's early stages. Consequently, brain imaging in young APOE4 carriers is being explored as a potential tool for identifying individuals at the greatest risk for developing the condition.12