Vascular dementia

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 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.

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.