The most common causes of dementia include Alzheimer’s disease, vascular dementia and dementia with Lewy bodies although some people develop multiple types of dementia; known as mixed dementia. There are also rarer types of dementia that are caused by other diseases and conditions.


Although the risk of getting dementia increase as we age, people in their 40s and 50s can also have dementia. The term ‘young onset dementia’ is used to describe any form of dementia diagnosed in people under the age of 65.

Read on to learn more about the causes of dementia:

Alzheimer’s Disease

Alzheimer’s disease, which is the most common type of dementia, is a physical disease of the brain. This occurs when brain neurons are damaged by the build-up of proteins called amyloid and tau around them, which then affects the way they transmit messages. These changes may affect the whole of a person’s brain or just part and are progressive.

Vascular Dementia

Vascular dementia is the second most common type of dementia which can affect any part of the brain. There are 4 types of vascular dementia with different causes, but all are related to the flow of blood in the brain and the resulting damage to brain cells because of this.

Lewy Body Disease

Lewy body disease is a type of dementia caused by Lewy bodies which are clumps of protein that build up in the nerve cells and reduce the levels of some important chemicals needed to send messages across the brain. This then leads to the death of nerve cells. Many people with Lewy body disease also have the build-up of the other proteins that cause Alzheimer’s disease.

Frontotemporal Dementia

Frontotemporal dementia is one of the less common types and is sometimes called Pick’s disease. This is the name given to damage in the front (frontal) and side (temporal) parts, or lobes, of the brain. As more nerve cells are damaged and die, these lobes get smaller and lead to more specific symptoms.

Alcohol related Dementia

This type of dementia is usually caused by the toxic effect of the alcohol damaging nerve cells and blood vessels in the brain, and because excessive alcohol can lead to reduced levels of vitamin B1 (also called thiamine) which is essential for good brain health. Further to this, a person who regularly drinks too much alcohol is at higher risk of repeated head injury which can cause lasting damage to the brain.

There are many other brain conditions that can lead to dementia. You can find out more about these via the Alzheimer’s Society UK website at