How does Alzheimer disease affect the hippocampus?

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Patient H.M. and short-term memory loss explained — hippocampus Learn about Henry Molaison (better known as “patient H.M.”), whose short-term memory loss following a lobotomy helped researchers to understand how brain structures are related to brain function.

In Alzheimer disease, the hippocampus undergoes massive cell loss. This significant degradation is directly associated with the memory deficits that typically manifest during the early stages of the disease.1

The neuropathology of Alzheimer disease is characterized by the presence of neuritic plaques—deposits of amyloid beta protein—and neurofibrillary tangles, which are twisted fibers of the protein tau located within neurons. These structures are thought to interfere with normal cellular functioning, contributing to the progressive damage observed in the brain. Additionally, the disease is marked by a deficiency in the neurotransmitter acetylcholine, which is vital for memory processes.2