How does neuron loss affect communication between brain cells in Alzheimer disease?

In Alzheimer disease, the progressive loss of neurons significantly disrupts communication between brain cells. Because these nerve cells are responsible for synthesizing neurotransmitters—the chemical messengers that transmit signals across the gaps between neurons—their destruction leads to a critical decline in these essential molecules.1

As the disease advances, the brain experiences diminished levels of key neurotransmitters, including acetylcholine, norepinephrine, and serotonin, as well as various modulatory neuropeptides. This chemical deficit, combined with the physical loss of the cells themselves, impairs the brain's ability to relay information effectively, contributing to the cognitive decline and loss of function characteristic of the disease. Additionally, the presence of neuritic plaques and neurofibrillary tangles is thought to further interfere with normal cellular functioning, though their exact role as a cause or consequence of this communication breakdown remains a subject of ongoing research.12