Dementia has more than one cause. Knowing the main types helps explain why symptoms can look so different from one person to the next.
Alzheimer’s disease
Alzheimer’s is the most common cause, behind about 60 to 80 out of every 100 cases of dementia.
Two abnormal structures build up in the brain. Plaques are deposits of a protein called beta-amyloid between nerve cells. Tangles are twisted fibers of a protein called tau inside the cells. Together they stop cells from working and communicating.
The earliest sign is often trouble remembering new information. Symptoms get worse gradually over a number of years.
Vascular dementia
Vascular dementia happens when something blocks or reduces blood flow to parts of the brain, so cells do not get enough oxygen. It can follow a stroke, or build up slowly from many small strokes.
Early signs can include trouble with planning and judgment, a shorter attention span, and trouble finding words. Depending on where blood flow is reduced, thinking can be affected without much memory loss at first.
On its own it makes up roughly 5 to 10 out of every 100 cases, and it is often found together with other types.
Lewy body dementia
Lewy body dementia involves abnormal deposits of a protein called alpha-synuclein in the brain.
Signs that stand out include seeing vivid, detailed things that are not there, acting out dreams during sleep, movement changes such as tremor or stiffness, and attention and alertness that go up and down.
Frontotemporal dementia
This is a group of conditions where nerve cells are lost mainly in the front and sides of the brain. Those areas help with behavior, personality and language.
Changes in personality, behavior or language are often the first signs. It is most often diagnosed between ages 40 and 65, which is younger than most other types.
Mixed dementia
Some people have more than one type at once. The most common mix is Alzheimer’s disease together with vascular dementia.
Research suggests mixed dementia is more common than once thought. Often it is only confirmed after death, so during life most people are given a single diagnosis.
Why it matters
Different types can call for different care and treatment. A doctor can work out which type is most likely, and what that means for the person and their family.