Physiologically, what happens to the brain as Alzheimer's disease progresses?

As Alzheimer's disease progresses, several physiological changes occur in the brain:

1. Formation of plaques and tangles: Abnormal protein deposits called beta-amyloid plaques and tau tangles accumulate in the brain, disrupting normal neuronal function and communication.
2. Neuronal damage: The accumulation of plaques and tangles leads to the death of nerve cells (neurons) in key areas of the brain involved in memory, thinking, and other cognitive functions.
3. Shrinkage of brain tissue: Over time, the brain experiences significant atrophy (shrinkage) due to the loss of neurons and synaptic connections. This affects overall brain volume and can be detected through neuroimaging techniques such as MRI scans.
4. Disruption of neurotransmitter systems: Alzheimer's disease disrupts the balance of neurotransmitters, chemical messengers that facilitate communication between neurons. Reduced levels of neurotransmitters like acetylcholine contribute to cognitive decline.
5. Inflammation: Chronic inflammation in the brain, triggered by the presence of abnormal protein deposits and the brain's immune response, further contributes to neuronal damage and cognitive decline.

These physiological changes ultimately lead to progressive cognitive impairment, memory loss, behavioral changes, and functional decline characteristic of Alzheimer's disease.