Vascular dementia is the second most common type of dementia. For every 100 people with dementia, 20 of those will have vascular dementia.

What is vascular dementia?

Vascular dementia occurs when blood vessels that deliver blood to the brain become damaged. Our blood contains oxygen and nutrients that help the brain cells to work properly.

When blood vessels are damaged, this reduces blood flow to the brain cells. So, brain cells don't get enough oxygen and nutrients. These starved brain cells then become damaged and don’t function properly. This is what causes symptoms of vascular dementia, like memory and thinking problems.

Sometimes this blood vessel and brain cell damage can cause memory and thinking problems that are mild and therefore are not diagnosed as dementia. This is sometimes called vascular mild cognitive impairment.

Causes of vascular dementia

There are different types of vascular dementia, caused by underlying conditions that lead to blood vessel damage. Not everyone is told the specific cause for their vascular dementia when they're diagnosed, and some people have more than one cause of vascular dementia.

Conditions that affect our blood vessels and reduce blood flow to the brain cause vascular dementia by damaging brain cells. The most common conditions that cause brain damage in vascular dementia are described below.


Strokes are a common cause of vascular dementia. A stroke occurs when blood supply to a part of the brain is suddenly cut off due to damaged blood vessels.

This causes damage to brain cells by reducing their access to oxygen and nutrients. If someone has sudden problems with memory and thinking after a stroke which do not improve over time, they may be diagnosed with post-stroke vascular dementia.

Roughly one in three people who have a stroke go on to develop dementia. Unfortunately, people who have a stroke are more likely to have more strokes, and so have a higher risk of developing dementia in the future.

People can have a series of smaller strokes, or ‘mini-strokes’, which cause progressive damage to the brain. Sometimes these strokes can be so small that someone may not experience any symptoms or know that they are having one. However, over time the repeated damage to the brain builds up and may lead to dementia. This is sometimes referred to as ‘multi-infarct dementia’. The word ‘infarct’ means that an area of the brain has had its blood supply cut off and the brain has become damaged.

Blood vessel diseases

Blood vessel diseases can also cause the brain damage that leads to vascular dementia. Some common blood vessel diseases are explained below.

Atherosclerosis is a disease where large or medium blood vessels get narrower, as fat deposits build up and clog the inside of the vessels. This limits blood flow through them and can make a stroke more likely to occur.

A diagram of a blood vessel with a fat deposit that blocks blood reaching neurons. The neuron is grey and dying because of the lack of oxygen and nutrients.

Cerebral amyloid angiopathy (CAA) is a disease where a harmful protein called amyloid builds up, making blood vessels narrower and leakier. This increases the likelihood of a stroke occurring.

Small vessel disease (SVD) is when small blood vessels deep inside the brain become damaged slowly over time. The brain cells supplied by these tiny vessels don’t get enough oxygen and nutrients because of the reduced blood flow. Because these small arteries only supply a tiny area of the brain, at first the damage to brain cells rarely causes any noticeable symptoms. However, over many years the damage can spread and may lead to dementia symptoms. The gradual decline caused by SVD is different to the sudden change in memory and thinking that can happen after a stroke.


You can find more information about the causes of vascular dementia in our blog here.

What is vascular dementia?

This booklet aims to help you understand more about vascular dementia. It gives an overview of the causes, symptoms and treatments.

Sue Strachan - Photo credit Alex Wallace
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This information was updated in December 2023 and is due to be reviewed in December 2025. It was written by Alzheimer’s Research UK’s Information Services team with input from lay and expert reviewers. Please get in touch if you’d like a version with references or in a different format.

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