The Nervous System

Alzheimer's disease disrupts and destroys the brain's ecosystem by devastating what scientists call a neuron forest.

Your brain is made up of an estimated 100 billion specialized nerve cells, or neurons. Each neuron consists of a cell body, one or more specialized branch-like extensions called dendrites (which receive nerve signals), and a single axon (which sends or transmits signals from the cell body to other neurons).

Neurons contain chemicals called neurotransmitters that enable cells to communicate across tiny gaps called synapses. The tens of billions of neurons in your brain connect at 100 trillion points.

When a neuron is stimulated, it receives messages from other cells. A tiny impulse, or electrical charge, builds in the cell body and travels to the end of the axon. There, it stimulates tiny sacs that release neurotransmitters to enable communication between nerve cells across a synapse. The typical neuron has up to 15,000 synapses.

As Alzheimer's disease takes hold in the brain, neurons stop functioning, lose connections with one another, and die. The death of many neurons causes vital parts of the brain to atrophy, devastating your ability to remember, think, and control how your brain and body behave.


Scientists have discovered unusually low levels of acetylcholine, a neurotransmitter critical to learning and memory, in the brains of people with AD. The neurotransmitters serotonin, norepinephrine, somatostatin, and GABA are depleted in nearly half of people with Alzheimer's. Neurotransmitter imbalance can contribute significantly to insomnia, depression, aggression, and mood swings.

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