Reference
What is Alzheimer's?
Reference B · October 9, 2026
The basics of Alzheimer's: what happens in the brain, how the diagnosis is made, what can be treated – and what a diagnosis actually says about the future.
A diagnosis is not a prognosis
Getting the diagnosis of Alzheimer's is a shock and an upheaval. It is easy to immediately think of the late stages of the disease.
But Alzheimer's usually develops slowly. The diagnosis says that a disease process is under way in the brain. It does not say exactly how quickly it will develop in your case.
There are often many years of life left to live.
What happens in the brain?
Alzheimer's gradually damages the nerve cells and their connections.
Two proteins are particularly important. Amyloid can form plaques between the nerve cells. Tau changes and accumulates inside the nerve cells.
But Alzheimer's is more complicated than that. Inflammation, blood vessels, metabolism and the brain's energy supply are also parts of the disease picture.
Alzheimer's and dementia are not the same thing
Alzheimer's is a disease. Dementia is a condition where cognitive problems have become so large that they clearly affect everyday life.
Alzheimer's is the most common cause of dementia, but there are several others.